They put out a lot of hurt though, you just gotta play them carefully, and choose the right targets. Deepstrike, and an 18" range helps with this. I've seen the plasma squad just obliterate tanks. 2d3 shots each can really add up. Especially with the deathwatch re-roll wounds, and a captain nearby.
If you can apply pressure with other units, and keep the inceptors back, they can live longer than one turn. If your whole army is in your deployment zone, and you drop the inceptors in, they will die the turn after they shoot.
The bolter versions I think are brilliant as well.
I think I'd always take these guys over hellblasters, just due to the mobility they have. They'll probably have the same number, or more shots than a hellblasters squad anyway.