Why would Canon want to upgrade the MP-E 65mm ? It has very little competition, and (according to reviews) is an excellent lens.The MP-E is a wonderfull lens, optically. In my opinion has some big design flaws.
1-It has a 6-blade aperture, which gives awfull hexagonal outofocus highlights
2-Has a full sized front lens, were the glass is small. Ideally should have cone shaped tip, like Olympus auto macro 38mm and 20mm bellow lenses
This the a lens I really have been waiting for; how long can it take from a pattent being made and the lens finally released?
I will work with bellows until then