Mine hasn't been modded in any way. The digital back is a Phase One H101 for Hasselblad, so yes, it would normally require a Kapture box, which I don't have, but I learned how to use it and operate it without the box. Kind of like using it in bulb mode and letting the camera fire its own shutter speed. The digital back literally functions like film emulsion in this case, being sensitive to light all the time. I haven't used it with flash yet, though, so I don't know what you're saying.
The mount I used was also DIY'ed out of a non-working film back. It worked perfect but with a 5mm recess. I will be 3D printing a precise holder to counter the 5mm recess thing in January.
The sharpness that I was able to get out of this, and the Fujinon EBC lenses, has been so far unmatched even by my recently acquired Canon 70-200mm f2.8 L IS MARK II on a 5D Mark II body!!! I can't believe this thing existed so long ago and still kicks so much ass. Colour reproduction and contrasts are also faultless. The only downside is the slow process. The iBook I'm using is old, so I shoot tethered to it, move the files to a newer computer and use Capture One there to process the files. Anyone with a newer Mac can create wonders with this.
I can share a sample photo (of my neighbours roof) if you want, just a bit too busy right now to upload and share and link. PM me if you're keen.