I'm noticing this to be the draw back of the Halo. So far I've noticed the 510's to be the thread of choice. I'm a noob though, I could be wrong.
It's a bit of a drawback, but not much. You can fit anything except eGo threading on the Halo with an adapter.
510 is the most common, but that doesn't necessarily make it the best. You'll find a LOT of substandard 510 parts. 808 parts tend to be of higher quality because there are fewer cheap Chinese copies of 808 threaded products.