Well if you just want it to learn. I would go with the Canon XL2. It is standard definition but has interchangeable lenses and all manual controls.
Nice cam for its age, but SD kinda makes me cringe. Is there anything comparable that shoots 720p or 1080p for $3-4k aside from JVC HD100?
Also, couldn't I just get a 35mm adapter to learn DOF on? I have one on my HV30 now.