Hack the shit out of that thing, I have been doing that to mine for years now, best decision always.
That's the reason I decided on a PSP over DS anyday. If there's anything I can get out of it, it's the processing power of it, and all the things it can do with homebrew stuff and an enhanced firmware.
I mean, outside of the PSP features that came with it (video (Format Factory is a godsend here), images, music) I get to play the Game Gear in a (more) lightweight handheld form again (plus games I always wanted for it as well, and without the hassle of changing cartridges), I can play Gameboy games handheld and so on (with the added options that emulators provide *cough*savestates*cough*; and the additional buttons for rapid-fire). So what if UMDs are no longer being made? Most of the games I have on it are digitally in there anyway (except the 3 games I have UMD anyhow; let's not forget, I can play internationally (no longer US-game bound) since cracking it), and even so, I play my emulated games more than the PSP games anyhow. It's still one of my smarter investments, considering all the use I've gotten out of it so far. Makes long trips more tolerable, and lunch breaks more fun; and having at least 2 4GB flash drives does help.
I kinda wish the firmware guys kept up to date though. (Looking at you M33 (still at 5.00 M33-6)). To play it safe, got myself a Pandora battery in case I brick it. So far, no brick.
EDIT:
Dissidia is pretty fun and somewhat worth it, but there will be grind sessions here and there. Easy grinding AP-wise, just keep on killing lvl 1 characters until you master skills on a +AP day, and if you don't want to level up in the process, make sure a +EXP day is not on.
If you want to get achievements, but not want to affect your story run (like me, AP > EXP, for fun's sake; or keep a low level), just unlock a character on the dark side, and play as them instead.