I'm in the camp that the best thing you could do for your husband in this case is to get him a solid manual focus camera and guide him through the learning process. I'm personally partial to Canon FD systems, especially the F1. Yesterday, I picked up a wonderful F-1 and a 50mm 1.4 lens for US$220 -- a not unheard of deal. I'll bet you could get an FTb or TX and a 1.8 50mm lens for under US$100 if you look hard enough.
Here's a couple of links I found that discuss the problems with autofocus, the good points of manual focus, and why even an autofocus camera set on manual could be considered inferior to a manual focus camera.
If your husband wants to branch out to medium format, there's only a few cases where the camera will be autofocus (maybe only one? I'm not sure). He's more than likely to be using manual focus, so the better foundation of focus skills he has, the better, IMO.