walkinthewalk - the space issue is pretty much a deal breaker. I started out planning for 12 x 12 stalls, but given that Harley is so small and is very happy in his current 12 x 10, I thought I'd increase my aisle space. The stalls aren't done yet, so I can still change the layout, but if I have to go 12 x 14 that messes up everything.
ShirtHotTeez - yes, I considered cost of feeding him, but it's not prohibitive. He's on 100% hay currently, and is eating one bale a day compared to Harley's 3/4 bale (which will probably be less once I start using the slow feeder nets - currently, they just throw all the hay out in the paddock and it really gets spread around, resulting in a lot of waste). Still, you're right, it all adds up. Plus, whatever the cost will be of providing him with supplements, etc. for the arthritis.
Jan - yes, a QH is much more our type.
While I was at the barn trying out the big guy, I met my trimmer who has her horses there as well. She and I had a long chat and she showed me all four of hers. They are all Harley-sized (we're about the same height and clearly have the same taste in horses)! LOL A cuter bunch of horses, I have rarely seen. And all the picture of health. I would have bought any one of them on the spot if they were for sale. I tried to convince her she had too many, but to no avail :) She's really terrific though, and spent a lot of time discussing Harley's diet and skin issues. She agrees that he has dry skin and needs some dietary adjustments. We agreed that when Harley comes home, we will work together to come up with a feeding plan. She's really awesome and I feel lucky to have her as a trimmer.