This camera is pointless without a built in flash.
Once you attach an accessory flash it is no longer compact, totally defeats the purpose.
Will be sticking with the GF1.
Is the built in flash useful in your GF1?
The built in flash was used constantly on my Contax T3, my Canon S70, G9, S95 and used nearly every night on my GF1. Really can't live with out it.
I'm fine with my "flashless" 1Ds3 and 5D2... but neither are intended to be pocketable. Popping on the 580EX2 just makes an already massive camera a little bigger, I'm fine with that.
Jizzz, you lucky night wild animal
But seriously speaking I think it really depends on one's needs. I - for instance - not too often make pictures in the night, except the moon, sometimes. In such a case even 580ex2 nor even one paired with 430ex2 won't help a lot (or I just didn't notice it)
Seriously again, that's obvious, that it's always better to have even a led flash than nothing, but just for me it wouldn't be so crucial.