I don't see how I can be wrong when I own two Fujitsu ductless mini-split systems consisting of two outdoor compressors, two ceiling cassettes and three wall hung units. Ductless mini-split sounds oh so lovely in the brochures and it was the only solution that would work for our house. But what a royal pain to get installed. We had bids of $13.5K, $15.5K, $22K, $23K, $25K, $30K, $30K. These were essentially for the same system. Most installers when they first bid really screwed up the bid. We had everything from a single unit for the entire house in the ceiling that would be huge and somehow the cool air would migrate into the other rooms, to systems that only cooled the north side of the house but left the rooms with full wall glass on the south side uncooled. They did this as installing the units on the North side is easier. We eventually worked out for ourselves where we wanted the units and the size that they should be and had everyone bid against that. We had to go through two contractors. The first wasn't installing anything according to the installation manual. The second had to come out and redo the entire system after the city inspection. So far it has worked exactly one time when we turned it on. The other times we have needed a call to the company who then comes out and fixes it. It then works for a while until the refrigerant leaks out again. Both companies we selected were recommended on the Fujitsu web site as certified trained installers. Hopefully come summer all the kinks will be worked out. We didn't have a choice for AC for our house because it wasn't physically possible to run duct work without having it show in the ceilings but the original poster does so I am providing them with our experience. Your experience may vary so feel free to post about that. We had bids for Fujitsu, Mitsubishi and LG systems. They all were super expensive. The Fujitsu was the best fit for cost and types of units for us. Oh, and I ordered the system in June of last year. It took about 3 mths for the parts to come in. Then the first installer started to put it in until he gave up and pulled it all out. Then we had to get a second company to bid, put it in and get it working. Just this past March it worked. So about 10 mths from start to finish for this product. Probably a whole year as we spent a couple of months researching cooling options before placing the order in June. If we had a traditional AC the whole process would have been alot quicker, less painful and cheaper.

Ductless mini split or ducted mini split. In addition to the trade-offs that you mentioned, the controls might be better for one option or the other and one brand over another. With my Mitsubishi multi, mini splits, I can not set a true set-back. The remotes are only capable of timed on and off. Filter service will be easier with the ducted system. You will have one filter to deal with. Do your LG heat pumps have electric heaters? IIRC, one brand does, maybe Sanyo or Toshiba. I don't know what to tell you about the baseboard heat. You probably have as much experience as anyone using the mini split system. If you put in a ducted system, they can put electric heaters in that, but I don't know if that will coordinate well with the manufacturer's thermostat. Ducts result in duct losses, no doubt. You have some heat transfer and they leak right off the bat. The leaks only get worse over time so they need some work now and then and no one ever does that. Do you have a local air supply for the fireplace? Otherwise, they are a huge heat hog sucking warm air out of the house.

Don’t get me wrong, I believe that room feels colder to you and it needs help. If by laser thermometer, you mean an IR thermometer with a laser indicator, try something else or be sure that you are using it well. They are quite dependent on the type of surface that you point them at. If you are measuring on an identical surface in each room, your are OK. It can be as simple as a small stack of the same size envelopes, or identical pillows with identical pillow cases,use your imagination. Otherwise, a couple of quickly equilibrating spirit thermometers that have been compared to each other and a correction factor applied are better. The most simple way is to just use one thermometer, but that is time consuming and the temperatures might change during the process. I don’t think that anyone can say that the zoning is “incorrect”or not. We don’t have enough information. If there is a large temperature differential between two rooms on the same zone, the ratio between heat loss and heat provided is different with those rooms. Assuming that there is nothing wrong with the heating system, you need to cut the heat loss or add some heat in the problem area. Adding a little baseboard or higher output baseboard should not be terribly complicated or expensive. You need a hydronics person to check out your system and make sure it is working correctly. If it is, and you decide to add heat, that person likely, or his company, can propose that addition and give you a cost. If that is an oil-fired boiler, you need to have it cleaned, inspected and possibly adjusted, annually. If you don’t, you risk running inefficiently and a high probability of unexpected mechanical failure. The people that do that work are, likely, the same ones that install additional heat and may deliver your fuel oil. Lots of companies do all three. Perhaps that sticker on your boiler names an outfit that knows your boiler well. I Is natural gas available in your location?

"What you want then is a zone system with controls dedicated to putting the air & controlling the system how you intend to." This is an example of prescription without any analysis. First, the home is already subdivided into two zones, each served by its own HVAC system. The system which heats and cools the master suite also serves the exercise and laundry rooms. Taken together, these rooms are roughly 1/3 of the total heating and cooling load of the home. Assuming the manual J calculations are correct, the master suite makes up 65% of the cooling load of the system with the laundry and exercise rooms making up the balance. Unless the OP is taking in laundry on the side, the occupants will spend the majority of the time in the master suite vs. the laundry and exercise room. Simply locating the thermostat in the master bedroom will provide temperature control in the master suite--and for 2/3 of the load on the system. Sub zoning this system would enhance temperature control of the laundry and exercise room. The former is a room no one wants to spend time in, and the latter is one that involves intentional sweating. In terms of energy conservation, the OP would be investing in zoning to fine tune less than 12% of the home's heating and cooling load. That's a recommendation that should go in the trash can (to help ensure it's not one that gets recycled.) The design issue is supplying the required amount of conditioned air to the master bedroom for heating and cooling and introducing it in a way that provides proper mixing to avoid both stagnation and drafts. That's not a manual J issue, that's what manual D and manual T are for. Given the geometry of the master bedroom, I think introducing conditioned air at two points with the return on the other end of the room will provide better comfort. The HVAC designer should be able to compare that configuration with the single supply so the OP can make an informed choice before spending an additional $500.