Thanks for all of the input everybody!
I was riding one 3 yr old OTTB in a dressage saddle until I lost access to the saddle (I was borrowing it and the owner wanted it back), and had no issues. From then until he was sold, I worked him in his owner's jumping saddle. I more recently rode another young OTTB in my close contact, and as I mentioned, have been riding my boy in the close contact.
There is nothing wrong with my close contact (love the ability to feel his sides--one reason I returned the dressage saddle I was trying out!), but I do feel that a tad deeper seat, the ability to have a longer leg, and be able to better keep my leg under me will help out a lot with my leg issue, in addition to his training/my riding.
I was a little put off and baffled when I was told this about "no dressage saddles for young horses", especially since the person who told me has a 5 yr old OTTB and does dressage, so always uses a dressage saddle. Granted, her horse has been off the track and in "real" work longer than my boy, but still...
I could see this viewpoint if it were a beginner rider who slams down in the saddle (deeper seat making the issue worse), but I am not a newbie and do not bounce around like a sack of potatoes.
The saddle I tried out had a deeper seat and had knee rolls too big for my liking. Here is the saddle I just bought. It should be here on Friday!