Yes with the new rules stealthsuits are going to be seen a lot more now.
heh heh 'Stealth suits will be SEEN a lot more'
Anyway, I've used Stealth Swarms in lists before. They're fun on paper but were hugely impractical in previous editions because of mixed saves and the neigh impossibility of getting effective use of cover.
Plus they're just a pain to move.
Now though? They're looking pretty decent. Just remember though, you still need to actually use cover.
Stealth Field Generators now give SHrouded and Stealth, meaning they get a +3 to cover saves (Max 2+), so out in the open they've only got a 4+ cover save (which is still great)
They need to actually have some kind of 5+ or better cover to get that terminator cover save, so with that huge unit floating around and the tougher rules on cover you;re still going to have to work for your saves.
Also worth noting: Gun Drones are some of the tau's best asaault units. They may be WS2 and A1, but they're I4, which is a big plus. I don't suggest charging your land raider expensive stealth swarm around the board like they're Death Company, but at least with that many of them you'll do some damage if they get stuck in.
As with all point sink units, they can be supremely effective, or a big anchor to drag your list down. It all depends on how you use them