"Gas is not an option". I'm assuming you mean natural gas. You all ready have propane. Are you opposed to keeping it?

If you are going to make the investment in radiant you may as well do the whole place. While this is primarily a summer place if you are going to "do it", do it once and do it so if you change your mind and decide to go full time or decide to sell in the future the place is ready as a full time occupancy.

VT was my territory in my business for 25 years in the HVAC/P&H industry. My suggestions is to eliminate the old duct work (google "DOEductleakage). Install a combination of Fujitsu mini-split heat pumps and at least one Rinnai Energysaver depending upon lay-out. That is how I heat my home. Very efficient and one system backs up the other. That is very important in VT when you are not on-site to prevent freeze-ups. Where exactly are you in VT? FYI, my customers in VT (heating distributors and contractors) estimate that about 4-5% of all apts and homes in the state have the Rinnai's in them. VT is great country. We miss it!

Have rinnai's in the barn...will take a closer look for inside the house. Propane is an option...and yes, did mean natural gas.
Told radiant won't work with the old wood floors ...and would be patchwork, so we are pretty much deciding against it.
we are in Halifax. Your thoughts are great, going to do checking on the mini split heat pumps too.
thanks so much.