Someone was working on converting the XPH rules into d20 modern advanced classes which got me excited about putting together a psionics game. After writing some scenes and working out factions and some backstories I realized that I would want something entirely centered around psychics such that most, if not all, PC's would have a psionic class of some kind.

In light of that, what would be the pitfalls of simply adding the D&D 3.5 XPH (and Complete Psionics) to the Modern library for the game? I already know I would have to edit skills, add a Defense and Reputation progression to each class.

Classically Modern is the answer to building new classes (psionic or not) and incorporating new psionics in a balanced way. Link:

http://www.freewebs.com/merlinsworkshop/CMsap.htm

Yes, I've seen Classically Modern and it seems to be a great standalone product. It really took off on its own and rebuilt the ideas from the ground up. That might still be a possibility. However, I'm looking to see what is issues might be with two products that I am already familiar with but never combined together before. If there aren't any then I can put together a game that I am confident in without having to read a whole new system, or asking potential players to do the same.

IMO, it'd be reasonable to just copy and paste the stuff from XPH. The rules are slightly different (no big deal) and XPH powers are generally a bit more powerful. Also, depending on your game, certain powers may be problematic in a modern setting (take note of what they did to the arcane spell lists in d20 modern). Other than that I'd think that a conversion would be reasonably straightforward.

Alright, if there's no other opinion...

Thanks weishan for your help. Hopefully it's not too niche to get players when I am ready to run it.