Beware that I have came across a few USB extension cables that would work fine for everything else but the iPad would say not charging even when using the 10W adapter. I am aware that the iPad was still charging but at a lower rate. I never felt like investigating why it was happening.
That is an opinion. I would much prefer a singe cable than two cables as would many others.
I have never experienced an issue with charging (using an official Apple brick, Apple cable, and extension...). Not saying it can't happen, but I've never seen it. I HAVE had issues charging with aftermarket "long" dock/sync cables (as many have).
And no, it's not "two cables" if you connect them... the fact that you can seperate them doesn't make it worse. By that logic, since I can take scissors to my one cable and cut it in 2, it's somehow "not as good".
You aren't toting 2 cables, you are toting one. It just happens to be joined at the usb port. Not sure why that's such an issue...
And the advantage is, if I DO want a shorter cable (and have one connected to an extension for example) I don't have to go running for a new cable from somewhere, I simply DISCONNECT it and VOILA, shorter cable.
It's better in almost every respect.
Until Apple releases an "official" longer cable, a longer "aftermarket" cable isn't any better than an extension. Many would argue it's worse (and less functional).