The choice I had for my Sergeant Sniper was either Suppression, {which might have been awesome with the Plama Sniping Rifle}, or Rapid Reaction, {a second reaction shot if on Overwatch and the first hits}. I don't know if I'd play with training roulette next time, but it certainly has been fun.
btw: I chose Rapid Reaction.
I bet the choice for Corporal was tough...
Snap shot is more useful in EW since they reduced the penalty down. Now you can offset it by adding a scope, and I've got a SS sniper who's actually very useful on maps without a whole lot of long sightlines.
He's using the Training Roulette. If I'm not mistaken, that's Run and Gun. It might be useful if one of the future advancements is Snapshot, but you can't determine that ahead of time now can you?
Under Training Roulette, snipers get their first adventurous choice at Sergeant, both skills can be new ones, they get one new choice at Lieutenant, to tempt you away from Disabling Shot, two new choices for captain, a new 'option' for Major, but their Colonel choices are specific to snipers, ITZ and Double Tap.
Run and Gun is specific to Squaddie Assaults, so you won't see it on another 'class'
I already had two snipers with Snap Shot so Juanita got Squad Sight and Archangel armour, plus, when I get enough Meld, the genemod that boosts the bonus for shooting from heights; Depth Perception +5 Aim & +5% crit.
Sorry for taking so long, but it's the first cool day, {sub 45C/113F}, for two weeks and had to go hunting and gathering.....