We did a self install of a Mitsubishi Ductless AC and Heat unit in the island camp 4 years ago. With the limited temperature range of the island season it has really worked perfectly at heating and cooling the camp. I was always afraid of what would happen on the island if I ever needed service.
I got my answer after two years when a nut on the refrigerant line cracked.
We called Home Energy Products in Belmont. They sent out a couple of young men who seemed delighted to take the boat ride out to the island and fix our problem. They figured it out and explained that Mitsubishi had been having trouble with these nuts cracking and they had been redesigned on the newer units. After the fix and recharging, they informed me of the bill, I was quite surprised at how reasonable it was. Then we packed up the boat with all their gear and headed back to the mainland.
The heat pump sure beats dealing with propane out on the island. The over sized unit really heats the cold camp in April and October as well as doing a quick cool off in July. The heat pump is cheaper than propane during the island season temperature range.
We ended up installing one back home last year. 15 seer I think.
I would recommend this company.
www.homeenergyproducts.biz