I mean, there is a third sniper option: a pile of Grotesques with Liquifiers. You can zip a Raider with 5 Grots in it up close, then melt him into goo with 5d6=17.5 autohits at at least -1AP.
I like the Torment Grenade sniping, though it does mean you're spending 3cp one doing one thing.
Something I just realised: vehicles aren't immune to Torment Grenades. Very useful for Dark Creed, who will otherwise be lacking in AT capability.