Well, damn. I forgot about Harker limiting Carapace. So! Forward Sentries in that list might be better, or Demolitions. Might just opt for Bastonne instead, though, with Carapace. With cover saves being as common as I expect, it might be moot to take Carapace, since the only place that would help is in assault, which I Veterans are terrible at anyhow.
Greatest flaw with 'Forward Sentries' is against Space Marines. Fought a forward sentries Vet Squad against 8 Sternguard - their Cover Save ignoring ammo wrecked what should have been 2+/3+ cover protected force. The fallback 5+ armor save was negated by the AP5 that went with the ammo.
Tactically, I was running 3 snipers, no special characters, and a second Vet squad with a Plasma Gun. I had moved out to provide interlocking fields of fire and cover approaches. My opponent just moved far enough forward to enter range, then shot (ignoring cover saves) and tore my flanks to shreds.
After a fallback and rally in a ruined building, my opponent closed within range, ignored all cover saves, picked out a few more troopers to bring my unit below 50%, then just waited until I failed a leadership roll and retired the field.
I think I killed 2, both with "lucky" lasgun shots.
Yea, well, I wasted 30pt on Forward Sentries, since Harker gives the squad Stealth, Infiltrate, and MTC anyhow. Why waste the points? Instead, I can afford to do more.
I have a Kill Team Tournament coming up the end of the month, but the TO said no USR's added. I am still going with Harker Vets, though. It should be suitable, since I am not expecting Sternguard. Might consider Storm Troopers, though. Depends on who shows up and I will gauge the metagame then.
I've been thinking of a Vet Squad w/ sniper, flamer, melta; and short Storm Trooper squad with a pair of plasma guns. And in a case like this, might be worth it to kit out the respective Sgts with the heaviest firepower they can get.
Harker seems custom built for Kill Team.