The larger the number of rooms that that you install mini splits in the higher the cost in comparison to a central system. Remember that you need returns for a central system. The choices are to have one in each room, install grates in between the rooms, install jump ducts or under cut the doors. Mini-splits have advantages in some situations. They are inherently zoned, so you don't have to cool the whole house for the dogs or you. Depending on your lifestyle, this might or might not save you money. What is installed in the USA is almost all variable-speed (inverter) equipment so it throttles well to control humidity under low load conditions. If you are on the costal plain, that is more important. It is humid down there. Typically, if a system fails you have lots of other areas to stay comfortable in. That also means that a modest generator will run parts of your system.) For me, a duct system that is outside of the house envelope is a drawback. First, ducts always leak even when new and they never improve themselves. That means everywhere you have a leak it equals a power vent either drawing in outside air into a return or blowing air outside. Keep in mind that also induces pressure differentials in your house so air is sucked in or blown out to balance that. Take a look at the Mitsubishi, Toshiba and Sanyo web sites and see what the mini split kingdom looks like. Keep in mind that in addition to the sterotypal high-wall indoor units, small ducted units (that handle more than one room) ceiling cassettes, horizontal ceiling units are available. You should see them on the web sites. They do cost more and are a little less efficient. Check out the different brands for how their controls thermostats) work if you decide to seriously consider mini splits. You obviously need more quotes given the difference between the two you already have.

I don't see any coils of excess line in my Mitsubishi systems. The installer, who has been teaching at a local trade school for at least 30 years, must have figured out how to cut them. He must have figured out how to charge a system too since a reversing valve failed under warranty and had to be replaced. I have no doubt that older systems may be longer-lived than newer ones, and less complex. That does not mean that the stone-hatchet stuff is better in every way. If we followed that logic, we'd all be driving the cars that they still have in Cuba. Learning new techniques can be challenging and training is expensive when you consider the time needed, but it is necessary. The down side may be that it puts small shops at a disadvantage. I don't see how one or two people can afford to stay current on everything that is out there today. It is not limited to cooling either. Right now, I've been dealing with a boiler replacement at my dad's house and trying to do it on a reasonable budget. Putting a low-mass boiler in his old hydronic system (without a lot of expensive modifications) is a challenge. Finding a local installer that is up to date in his rural area has been frustrating. (Small here is really small. Katy is huge compared to his town of 2000.)

I have no experience with heat pumps in an area that cold. I understand that they are getting better all the time, but I don't know how they will do in your coldest weather. Cost will depend a lot on how many rooms you have. If it is an open floor plan, cost will be lower. If you have lots of walls and doors, the cost will go up as the number of units increase. Ducts are bad when they are outside of the house envelope. Design your house with indoor ducts if you go that way. Ducts are bad when returns are inadequate causing pressure differentials between rooms. This, just like leaks in outdoor ducts makes an air handler into a power vent. Mini splits are inherently zoned, but what does that get you? Zoning is not going to save you that much energy with a well-insulated house. Heat transfer between rooms will be much faster than from inside to outside. Zoning for comfort and control might be worth it. I have seven mini splits inside on three systems for nearly 5 years. I live in a hot, humid environment in a home that was retrofitted with central and had ducts in the attic and crawl space. The original central system was done right with a dropped ceiling (9 to 8 foot) in the central hallway. Later is was messed up with outdoor ducts added. The mini splits perform beautifully for humidity control. Maintenance is higher with mini splits. At minimum, you need to clean filters for each unit instead of one, two or three. I am finding that maintenance of my Mitsubishi units is greater than that. Lots of dust gets stuck in the "coils" despite regular cleaning of the filters. The back side of the coils is difficult to reach if the units are near the ceiling. In addition to that, the blower cages get dirty as well. I am trying to figure out how to get the cages out to clean them without largely dissembling the whole thing. There are some characteristics of mini splits that some to not think of. Their performance measures are hard to compare to single speed central systems. My understanding is that they are locked into a constant chosen frequency (speed) and measured like that. In real operation, at low output, variable speed systems are more efficient than at high output. This can be a factor in choosing to use set backs, which can be counterproductive. My belief is that the manufacturers could fix that by allowing a set back recovery at less than 100% output with more sophisticated controls. My mini splits run very well on portable generator power. There is no start-up surge as seen with on-off units. They spool up very smoothly and slowly. If you have more than one system, you will never be totally out of heating or cooling. You might find this study useful. It was an eye-opener for me: Long-Term Monitoring of Mini-Split Ductless Heat Pumps in the Northeast Building America Report - 1407 December 2014 Kohta Ueno and Honorata Loomis

I'm not sure I understand how advanced you are in your planning, but some input: Ontario Hydro rates are here (may not be exactly right for where you are): http://www.ontario-hydro.com/current-rates Note the peak times change between winter and summer, and nighttime (from seven) to morning (to seven am) and weekends are all off-peak and lowest rate. Peak rate in summer is peak a/c time. So depending what your loads are, 'timing' your usage can make a big difference. Investing in some more sophisticated controls to favour using electricity at off-peak might be worthwhile, and possibly some 'heat storage' (e.g. heat your water at night, and even more complex arrangements). Since you won't have access to natural gas (the cheapest), what really makes sense is to figure out how well insulated you can make the house. The better insulated, the less need you should have for both heating and air conditioning. For southwestern ontario, depending where you are, the a/c season can be pretty short (although this year was exceptionally long), and with judicious use of ceiling fans, shade (in summer) in rooms where you spend most of your time, you may be able to get by with minimal a/c. Hydro's rates may seem pretty high but it's possible that some solar could make sense, if you can 'self-consume' all of your solar (which is always going to be at peak or mid-peak rates). (I don't know anything about feed-in tariff situation in Ontario). One comment, be cautious about putting a fireplace in the basement, draught/draw can be poor unless carefully designed. And if you go for a 'tight' house, they may recommend against wood-burning fireplaces.