The only benefit of having PS2 games in the PS3, is just the PS3 upscales the PS2 games. Not an important feature by any means. And another benefit would be having the PS2 inside the PS3.
If you really want to play PS2 games I would strongly suggest buying a PS2 Slim and having that. There you won't have to deal with the problems that some PS2 games would have on the 80GB PS3.
I have a PS2 and I might be buying a PS2 Slim sometime in the summer. I hate emulation. I'm playing Doom 3 (an original Xbox game) on the Xbox 360 and I notice some graphics corruption and the title hangs at the start screen. Weird problems like that makes me want to own the original console.
I just don't trust the 60GB now because the majority of them are used. So you can do the following:
1) 80GB PS3 and purchase a PS2 Slim
2) 40GB PS3 and purchase a PS2 Slim
3) Used 60GB PS3 and be able to play all PS2 games
The choice is up to you sir.







