Honestly, I see their Taurox spam as the stronger advantage, flyers are strong so maybe take 2 but no more than that under 2000.
At 1500 these guys are definitely viable. You have enough units to have specialised task forces and redundancy. Anti-tank, Anti-armour, anti-MSU (just lots of shots), flyers, Objective capturing trucks (who can and should tank-shock scoring units).
Drive up, get out Melta something, drop the units in Valkyrie off with more melta and pincer their armoured units paratrooper style. Follow that up with plasma squads in Tauroxes to kill the units that pile out. Once you've dropped men off drive away and go cap objectives.
Also a notable something: Units can embark in another units transports so any nearby Taurox can pick up a damaged Scion unit.