I haven't used both so I won't vote, but I got the Deathadder a couple of weeks ago and it's awesome. It's size and shape is very similar to my previous mouse, so I already knew I would feel familiar with it. It looks and performs great, the rubberized thingy also feels very nice.
My only complaint is that the glowing logo heats up the mouse, so I just turned it off after staring at it for a few minutes (remember to turn it back on when you have friends visiting!). And I still need to get a mousepad (currently using it directly on desk).. the Razer ones are too big for me though, I'm currently thinking of Ideazon or func.
But back to G9 vs. DA. From what I've seen in videos and photos, the G9 would be way too small for me, even with the wide cover. I don't have big hands either, I think it's just a matter of grip, so it would be good to compare the size of the mouse to your current one, so you could guess how it would feel.
Performance-wise, I guess they would be quite similar.