Could give plain space marines a shot, then... they've got an end-game building that's more or less a global detector (and reveals more or less the entire map at the same time). Most commanders are either natural detectors or upgradeable to being one, too, for what that's worth. Inquisitors have a detector unit that, while flimsy, has pretty ridiculous range, too... and that's discounting the Damocles stuff, or putting auspex on turrets (which are immobile, but the range is again huge) or somethin'. Most of the factions have at least a couple sources of keen sight that's both mobile (and/or with a massive detection range) and not-entirely-squishy.
@ tell; The total cost for a getting a vespid squad up to full health is 1,040 requisition. They are cheaper than the equivalent inq critters -- the GK Terminators, which come in full reinforced at 1330 req and 320 power -- but they're still pretty expensive darn expensive (you can buy up about two full squads of the lesser GKs for roughly the cost of a single vespid squad, ferex. Only has about 2/3rds the HP, total, but fairly significantly better in most other ways for the cost). Requisition cost is three dead vespids from equalizing, and the individual GKs have significantly better resistances, as near as I can tell. Plus overall better damage output, iirc. Bit worse at tying stuff up, though, true.
Seriously though, the vespids don't really seem that out of line with equivalent research stuff, cost/effectiveness wise. End-game stuff gets beefy, and for all their meat the vespids aren't that impressive in other areas. Don't really see them as a competitive advantage m'self, basically.