US, in the Tau FAQ & Errata, Stealthfield generators were re-written to simply confer the Stealth and Shroud USR.
I may not have the rulebook in front of me yet, but I trust the chaps who do, so Stealth Suits have a 4+ Cover Saver MINIMUM anywhere on the board.
I think I perhaps was misinterpreted, and misinterpreted in turn.
1. Shroud and Stealth stack. This is not in contention at all. Says so clearly in the core rulebook.
2. Stealth does not benefit from an additional application of Stealth, and Shrouding does not benefit from an additional application of Shrouding. I'm assuming this is not in contention.
3. Night Fight's conferred bonus defenses, when within 36" but beyond 12", gain either Stealth or Shrouding, while a stealth suit already has both Stealth and Shrouding from their Stealth Field Generator.
4. Thus, a Stealth Squad does not benefit from Night Fighting unless they are more than 36" away.
My earlier comment about "not stacking with itself" was, upon reflection, an apparently unclear version of statement 2. If my response didn't make sense, I apologize and hope the context clears things up. Sorry for the confusion.