No it doesn't replace the board amps at all. The board amps actually appear to be well designed. But as with anything the power going in matters, A LOT. That's where these really benefit. You could screw up the sound very easily by trying to muck with the actual amplifier, but I don't see any reason to do it when it's been show that improved power is well appreciated on these.
Yes I can still mod them but if we're talking 1 or 2 is two different things. Without 10 pairs committed to the level 2 the price is quite high. If 10 pairs are committed it drops $500-600.
When I populate things I charge double on parts and assembly would be inexpensive for these. The issue is that you still have to perform the removal of the on board diodes and bridge where they were so that the new rectification and filtration system will work. Oh and you have to cut wires from transformer in half and heatshrink-solder (a new thing on market) to the new wires that have a connector on them. That's pretty easy, just minding orientation, but the diode part is interesting, worming in with little side cutters to do it. The DENO is easy to install, which cuts down common mode noise if you use line level inputs.