No, not Flyrants. Flyrants are awesome, but what makes the list work are Crones. Crones win games, because fucken haywire man.
Er, Tyrants have Ignores Cover Haywire (auto-hit plus Ignores Cover and unlimited shots makes it better than firing two Tentaclids against anything but Flyers, and since when were vehicle Flyers relevant? Or able to survive Flyrants?) plus a Devourer, or two Devourers, which make for pretty horrifying anti-tank (or indeed basically anti-anything, and the Flyrant is waaay tougher and while Jink hurts them pretty badly, they don't suffer nearly as much as the Crone does). I think you'd be hars pressed to fit Crones into a Nid list that wasn't limited in detachments or something by tournament house rules; 2 min squads of Rippers and 2 Flyrants with Electroshock Grubs and 2x Brainleech Devourers is a legal Combined Arms so bring that ad infinitun, and a Malanthrope in one of the detachments would almost certainly be the way I'd run it.
Like many armies, you *can* make them super-hard to beat at the expense of nobody wanting to get steamrolled by your boring, unengaging army outside of a dedicated tournament, or you can make pretty decent casual lists out of it. For the sake of people playing you more than once, I'd go for the latter.
EDIT: Actually, that depends on whether you're going to a lot of competitive tournaments. From my observation, Brits will hate you and never play you if you bring a competitive list (one guy at my local club bought 9 Night Scythes full of 5 man Warrior squads and Stormteks when 6th ed dropped, used it for a month and never found an opponent for the army ever again, causing him to quit to go and play Warmachine and spew bile about how GW suck), but particularly in the USA competitive armies are regarded as the good type to have and you can find a lot of organised tournament scenes. Basically, don't bother with the 'lololol spam FMCs i will faceroll the game and make it unfun for everybody' if you're in Britain, but knock yourself out if you're in the US of A (for some reason, while we English are huge fans of one-upmanship, we also have a complex convention of fairness to make sure that you're legitimately superior or something).