My 510-T atomizers arrived today; I've used them all day, moderate vaping. Blew out the primer when it arrived, re-primed with three drops. No leaks, good flavor, good vapor production. Draw's about the same as a 510 filler cart. Holds about 12 or so drops. They last me an hour before I have to refill it; if you're gonna travel, pre-fill some spares.
Initial impression? Really good. We'll see how it behaves a week from now, but I'm pleased with it. It's a lot more convenient and I can actually *see* when I'm running low. But the cart is relatively small; it's possible there's some relation to the smaller cart size working better, or potentially just a re-design between the eGo-T and the 510-T.
As for what a box mod is, it's a double-A battery case that's altered to serve as a battery for an e-cig. I like the unit I got from Madvapes; it's not the most durable unit, but it's been very reliable. The 14500 rechargeable batteries for it are relatively inexpensive, and it has a built-in off switch. They run about $25 for just the box itself. Personal prefernce, YMMV.