I've played so many games on the 3DS that would have been improved had a dual circle pad scheme been implemented, that I probably would upgrade if they released a model which provided that. Is it likely? With Nintendo, who the hell knows? But I would certainly like to see it.
I might just have been really unlucky, but my original 3DS has so many issues. I don't like the shoulder buttons (which feel mushy), I'm not a fan of the face buttons (which could stand to be made a little bigger) and I really dislike the D-Pad which has always been squeaky. On top of that, the recess for the stylus does not hold it securely, the hinges for the top screen are very loose, and I think the tri-tone plastic looks dumb.
Basically, what I'm saying is that there's plenty of room for improvement.