I'd say unless you're extremely good at SMD rework and have all the necessary equipment then don't even think about attempting it.
You will have trouble replacing the StrongARM and the Phillips DSP as both parts have been discontinued and were apparently quite hard to source individually even when they were still being manufactured. The mainboard is a proprietory design made specifically for the empeg/riocar so that won't be replaceable... I think everything else is reasonably standard apart from the PIC controlling the display for which the firmware has not been released.
Most hardware problems are because of blown fuses on the board, bad IDE cables and knocking off the fill nipple on the VFD.
If all else fails and there is no longer any official support for the empeg (which hasn't happened yet) then you can always try to bribe Patrick Arnold to fix it for you
- Trevor