I think sacrificing an OV to scout right before your roach warren and baneling nest hatch to check his composition would be the best way to see for sure what's going on. If you scout bio you just go heavier on the banelings and less so on the roaches. You could even just forego the nydus if he doesn't have any banshees anyway. At this point you are basically doing a standard roach ling bling bust and can hit a bit earlier. You can also start your infestor tech and upgrades earlier since you are saving 300/300 from not using the nydus. The only plays that really stop this attack (no nydus, no queen) in its tracks are fast siege mode and banshees. It might not be a game ending attack but as long as you do SOME damage I think you can end up even if not ahead.

Think of it as a greed check? If he went 3CC and skimped on bunkers he will die. If not, the game goes on.

edit - See here: http://www.teamliquid.net/forum/viewmessage.php?topic_id=344272 for another look at this style bust, optimized without a nydus.