I owned and used the 45mm Tilt Shift Hartblei for 645. I had it mounted onto the Contax 645. I also owned and used the rarish 65mm Hartblei for Contax 645. I guess it all depends how a person uses a lens, and how quickly they need it to move, and how intuitive it is in their hands.
Before that, I owned and used all three Canon T/S lenses, and in actual shooting -- (No MTF charts here, folks -- actual photography for money, under pressure) -- I found the Hartbleis to be very awkward to use, and very slow to move into position, compared to the incredibly easy to use Canons. The first time I used the 45, honestly, the first thought I had was, "You've got to be kidding me".
My suggestion for anyone considering these lipsticked Hartbleis is to make damn sure you have a No Questions Asked return policy. I'm sure, under ideal conditions, in a 72 degree climate controlled studio with iTunes running in the background, a person might say that the Hartbleis are just fine. But I just found that, with that dark viewfinder in the Contax 645, and with the max Fstop of the Hartbleis, they were VERY hard to focus, even not tilted or shifted. (Remember too -- it's Manual Focus only).
And then, you're out their at sunrise or sunset, trying to twist those things into some kind of "creative" position, and then the depth of field is inches, and then the dark Contax viewfinder -- well, it was not ideal at all.
So just be forewarned -- especially at these new price tags that they're asking. Make sure it works for you, BEFORE the check clears.
Just one opinion.