I spoke with the owner today, and then made my decision. Aside from the owner riding occasionally, I will be the only one schooling the horse. I had concerns about his head tossing, and he agreed and also felt the teeth needed to be addressed right away (hopefully he heard my "by a vet" part...)
I am free to take dressage lessons and (when I'm ready in the fall) jump lessons. I'm going to put him in a different bridle/bit which I think will help after he's had his teeth done.
Ultimately, I reasoned with myself, I'm paying for emotional therapy ( ), a quiet, willing and friendly mount, a high end barn (did I mention the grooming area/indoor are insulated = warm!), with access to fabulous coaching and established friendships. Another girlfriend urged me to think of it as a challenge, to take before and after pics as he muscles and grows up. Even if I can't ride down the road, I can do lots of groundwork, grooming and chatting with friends.
Thanks for all your help everyone.
Chiming in a bit late, but I think you made a good decision, especially being the main person riding the horse. Green horse aside, the part board is worth what you want and are willing to pay. If you want the current barn and a quiet horse and this one fits the bill, great! You may be putting some training on the guy, but if you enjoy it, that's all that matters.
WWQ, good news!! As long as he makes you happy, the price is quite reasonable. He's much cheaper than a free lease or a purchase!! $300/month is cheap for all the therapeutic, emotional, and physical benefits!
Hopefully this gives you some happiness after what you've been through lately.