There is probably a good reason they put them on group buy... I was literally about to buy a backup one (mine is currently down), but I just discovered that they just released a 20w Vamo, and soon (if not already) they have a 30w Vamo. the 20w vamo is sold on FT
here, and I know they have the 30w out or comming out, since I saw
this. They're probably depleting their stock of 15w because they know sales are going to drop when the 30w comes available.
for my take, the new versions look munch better. The top cap was one thing that I always disliked about the Vamo series. The bevel didn't look right on all my atomizers, the new one has a flush mount top, which should provide an overall better look. If the tops are interchangeable, I might try ordering just a topcap for the older vamo.