I've gotten 4 T-atty's from volcano, differences are they have a fancy laser etched wave on the outsides of attys and batts, they work just as well as other ego and ego-ts that I've used. Only non cosmetic difference I can see is that there is a rubber o ring instead of
threads on the battery, the 510 connector is the same, but most egos seem to take a
threaded cone, the inferno uses a push on friction fit cone. The rubber o ring also can restrict airflow with the t-atty, so I took them off. Have tried their magma attys, not enough for them to fully break in, but they seem to be quite solidly made. I expect they'll last a while.
Volcano has really good prices, warranties and a coupon code (maybe only on your first order). Only downside is if you get regular USPS, they ship from Hawaii. There's also the 4% Hawaii excise tax, but the prices make up for it (and the coupon code, and reward points).
I haven't had the stuff long, but I'm happy with it so far.