With a dual fuel system, how were you planning on typing the hot water heat into the system--a dedicated hot water coil? I have seen hot water coils used in conjunction with air handlers. A heat pump would probably be a strong choice for your climate, since you say it's mild. Heat pumps heat and cool, all electric. If electric rates are reasonable, a good heat pump system is probably the way to go. You don't want to oversize the system, so you'll need to have a contractor perform a heat load to size the system. Heat pumps get sized for COOLING load, not heating load.

You can provide the details on Rheem/AmStd. quotes--all model numbers, work spectrum, etc. for more thoughts.

Thank you for your follow up message (ryanhughes). The 'Lifebreath' Clean Air Furnace/Air Handler (link in earlier posting) is the system we've been considering if we decide to use the hot water as the heat source. The quote we had on that last year was $8,200. We've been told that the airflow of an air handler over hot H2O pipes system doesn't feel as warm/hot as that produced by a gas fired furnace. Any thoughts? Heat is heat isn't it?
The latest quote we have for the Rheem system is as follows - Classic 90 (RGTA07EMAES and matching Rheem evaporator (can't read model # on faxed quote). Rheem 14 SEER (RPPL036IAZ) heat pump and Rheem dual fuel thermostat (RHC?ST400DFMS). Quote is $12,500. That's up from $11,600 a year ago.
Still waiting for updated American Standard quote. Look forward to your input.

My biggest fear with a hydronic system is that all systems will eventually leak. I'm assuming yours is going to be in the attic so even if its mounted with the proper drain pan and proper routing to a drain, your not going to see a leak until water drips from the ceiling because the leak is spraying or because the drain pan clogs. Wouldn't want it in my house. As far as "heat is heat" is concerned, the heat exchanger in a gas furnace is much hotter than the coil in a hydronic system or for that matter a heat pump system, so if the house starts out cold, gas will heat it faster. Once the house is warm it really doesn't matter. You should keep shopping though. I would get a bid on systems I liked from at least two different companies. They can vary greatly. Carrier and Trane make good dual fuel systems that qualify for tax credits as well. Because of where you live,you will probably never use the gas part of the system anyway. Don't know how much extra electricity your banking but you can also get an air handler with electric heat that is heat pump compatible so you wouldn't be venting burned gas fumes if part of your reason for going solar is to reduce your "carbon footprint". Again you'll probably never use the backup heat anyway. They gave you a quote for a 3 ton cooling system. Seems large for an 1100 sq foot home in your area. I'm also guessing since your into energy efficiency that you have good insulation and double paned argon filled windows. Did the contractor perform a heat load calculation like ryanhughes suggested? See what size the next contractor tries to sell you. When you know what size system you want, you can at least get ballpark bids from reputable companies over the phone or even on line.