Hi everyone, I thought I'd share a "hack" I tried out this weekend. I ordered some spare parts from epson, specifically their MF and 4x5 holder for the new Epson V850 and used them for my Epson V750. They are much cheaper than the betterscanning alternative(BTW I also have the betterscanning holder). It has a pretty easy adjustment mechanism(adjustable thumb tabs in 5 possible positions) for calibrating the optimal height.

Pros:
No taping or creating masks to the glass as compared to the better scanning holder
Much easier to find optimal holder height(only four tabs to adjust) compared to using a mini allen key to make 8 adjustments for the betterscanning holder
Keeps the film much flatter than the V750/700 holder

Cons:
Its a bit tricky to get the film flush into the holder especially for the medium format holder as there are slots to fit the film under. I've found a couple of tricks(which can be googled) but either involves modifying the holder or touching the emulsion side...therefore I would really recommend thin gloves. It would have been such a minor design improvement to rectify this.