While I do agree with most of the stuff said above, I am in favor of a complete garchomp allowance, including SS + SV, for a couple of reasons. The most prominent is that SV is a crucial, broken (in my and most people's opinions it seems) ability only when talking about offensive checks to garchomp. However, sand veil is a largely irrelevant factor when countering garchomp with something like skarmory. Since the set in question is the subSD set, which typically has dragon claw and no boosting item, garchomp does not even 2HKO on average with a +6 dragon claw, and has no chance to do so if the skarmory holds leftovers. This means that in order for a skarmory to fail to check a subSD garchomp, sand veil must activate 3 times while the garchomp SDs, and then 3 times for it to kill the skarmory. The chance of this happening is (1/5)^6 = 0.0064% probability. This means that despite the hax-based element of sand veil, skarmory for example remains an incredibly sure-fire counter.
I also think that, although pocket's example of twave does not quite equal that of sand veil, a more or less comparable one is super luck. Crits are a part of the game, but that does not mean they can always be prepared for. Stall would be a non-existent entity if every set-up sweeper was guaranteed to get critical hits every time they attacked. And yet, we do not regard an ability such as super luck, which raises the probability of this "game-breaking" occurrence, broken. And while it is true that sand veil is a more exploitable ability, due to the possibility of "fishing for misses," super luck introduces the same element of battle that is simply impossible to prepare for. How many games have been changed because a terrakion stone edge critted on your gliscor? And yet moves like stone edge do not really warrant banning (and not just because of the accuracy).
tl;dr
While SV does limit the absolute reliability of garchomp's offensive checks, it does little to change the defensive ones. Furthermore, the game already has elements of hax that are impossible to prepare for, such as crits, full paralysis, and "contact status abilities", another somewhat complete parallel I see. So IMO all forms of garchomp should return to OU, even if it necessitates more defensive checks to him.
EDIT: also just wanted to say that, stepping away from theorymon, garchomp was incredibly underwhelming on the suspect ladder. Even when it dodged death, it's outsped by a ton of stuff and isn't that hard to revenge. True, it's very nerve-wracking when you just *have* to hit it in order to win, but I see that as very much akin to praying that you get a decent damage roll, or that the opponent doesn't crit.