This simple.
How much do you want a PS3 that runs PS1 and PS2 games perfectly?
That one you're eyeing is prolly one with those chips in it, so that the console does not have to rely on software emulation to run the older games.
If you wait, you'll prolly save money from an eventual price drop. Plus theres just not that many good games for the PS3 right now.
If you do wait, you'll prolly end up with a PS3 without the PS1 and PS2 chips in them, lowering it's ability of perfect emulation.
At least, that's how I'd look at it.