Without any buff, it's already impressive if you hit all 3 hits, without crit'ing any. With simply gear, I can say for sure you should be able to crit at least 1 from 3 hits.
Last Stand could be a superior alternative if you are using the highest damage bolt/bullet available. The reason why I haven't gotten a good number from Last Stand yet is more due to that reason. So I can't really give comparison yet; But it's still a strong contender to the highest WS damage RNG can pump.

If we're looking at Voidwatch, the -enmity from Coronach and the fact it's still well below Last Stand in term of WS damage, it actually doesn't give you much of advantage. Full-timing Gnostic's Drink gives me no hate problems in VWNM fights. I remember doing 2.7k Jishnu's 4x without holding back until the hate goes into me (and soon after PLD is able to grab the hate back). So for any VWNM fights where your group can restore temp regularly, I don't see much advantage offered from Coronach. As for less number of x-hit build, I can say I'm almost to the point of 2-hit build when using Harrier +2(WS -> 1 shot -> wait for couple secs -> WS)