It's absolutely not a gimmick. They wick fantastically well, better than anything I've ever tried. And the amount of vapor is amazing.
It's hard to comment on longevity as of yet, but mine haven't died yet, so more than a couple of weeks. Assuming you don't punch the center pole out the bottom.
They last forever, seriously. Mine have all lasted over a month. In fact, they never burned out on me, I break them sometimes when I clean them, I am impatient and not all that careful.
Wicking-wise, I can't tell you. Never used V1 much - I didn't want to deal with cracking tubes. All I can tell you is that after modding the XLs rarely give dry hits for the first half of the tank, and if you tilt for the second half, it's quite decent. Not as good as Visions though.
Like Erin said, the innards are not quite the same. The seals are quite different, and it makes a big difference to wicking.
Wicking is considerably better. No dry hits for me at all for Regs, Stretches and Nanos. All the way to the bottom. Longevity is probably a couple of weeks? I'm not a good reference for that, mine have been in rotation for over a month with no burnouts, but I have, like, six of them in rotation. I like to use several juices at the same time.
For the Stardust, they seem to be very well built, so I expect the longevity on those would be quite good. The ones I have have lasted over a month now with no sign of slowing down. But if you are using sweet juices, you have to clean those shorty wicks really well. Peroxide is good, right, Erin?

And, too, it seems that you can rebuild the coil and the wicks without too much trouble - there is a great video someplace around here.