I agree totally with audioengr in that it CAN be a great way to go but you better do your homework. This is to say that you shouldn't run out and have a mod performed just because of what you read or heard from others. I also feel it necessary to HEAR prior to purchase. The 1st level mod, changing out caps, resistors etc. for different more expensive ones won't necessarily give you a better end result but it is relatively inexpensive and easier to change back. The one area where improvements can be vastly improved are in the power supply as he mentions but this is risky business, you better know who you are dealing with and not be guessing or hoping about the end result. If in doubt DON'T DO IT! Some of the biggest "bang for buck" improvements in an component can be realized through modifications but again, they aren't all created equally.
The real downside to modifications, as mentioned, is that you will most likely not capture your initial investment unless purchasing used and the modifications have been performed from a known and respected business, cavaet emptor!
The real downside to modifications, as mentioned, is that you will most likely not capture your initial investment unless purchasing used and the modifications have been performed from a known and respected business, cavaet emptor!