Reavers with Heat Lances aren't just for their killing potential, either. They play some pretty serious mind-games on the enemy when you turbo-boosted them up behind their big vehicles first turn.
This. One hundred percent this.
My teammate and I won a 1000 points each 2v2, Dark Eldar and Eldar vs Grey Knights game because my two squads of three Reavers managed to soak up a HUGE amount of attention while A), my Archon and his four Incubi tore through two Strike Squads and Crowe(thank you Runes of Witnessing for negating his psychic power. <3), and B) my teammates missile launchers ate up their transports and Dreadnought.
One of the squads took two turns of firepower to take down. The lone Heat Lance guy ended up FLEEING, and the other squad weathered a turn AFTER that and managed to get into shootin' range of a Razorback. Even though he missed and the squad was destroyed the next turn, that shooting could have directed at my vehicles or my teammate's ultraviolent Dire Avengers.