The difference between the K3003 and ASG-2, to these ears, is significant. The way I'd describe this very briefly is, the AKGs sound more correct / realistic-sounding than the G2s... quite a bit more correct / realistic-sounding, in fact.
I tested several tracks but in one, in particular (see link below), the differences were pretty significant, where the G2s sounded rather congested and somewhat muddy in comparison. The K3003's transparency was markedly more apparent—percussion sounding as it should (big difference here)—and the low frequencies on the AKGs sounding very right, not thin, not bloated; the G2's low-end, by contrast, sounded boosted, unnaturally so. That's not to say the track sounded really bad / awful on the G2s, but it clearly sounded better on the AKGs (no golden ears needed here, in my view).
On well-mastered albums the K3003s take the cake without a doubt. On bright-sounding recordings (mostly modern pop and rock) the G2s sound better while the AKGs still sound very good — the K3003 is undoubtedly a better all-rounder as it handles practically any genre or mastering/recording quality with aplomb or at least, on poor masterings, quite competently. Orchestral works are not meant for the G2s—they don't sound horrible, but they lack air, space, transparency and can sound a little too thick, the busier the passage, the more evident this becomes.
http://www.youtube.com/watch?v=mqLxfFEzw5I
Perhaps idsynchrono, who now has a pair of K3003s in his possession and also owns a pair of ASG-2s, can chime in…and tell our FA4 & K3003 fanboy sparrow the AKGs are good, yes, but not quite that good.