I'm just finishing (got to bleed them and check for leaks) a power front disk conversion from Master Power. I wouldn't call it a peice of cake, but it hasn't been too bad. Biggest PIA was drilling the hardened threads out of the pedal support (need a 1/2 drill) for the booster, and then fabricating the lines to connect to the factory ones. This was harder because the old ones had to be cut off at the distribution block and it was my first attempt at double flaring the lines. If I'd done it before it would have been easier no doubt.
The disks and rotors, soft lines, etc. bolted right up to the drum spindles.