Currently, it's safest to assume that you'll get the limit on your ticket and not a gram more without being charged for it. It doesn't matter whether it's low cost or a full service legacy carrier, I've seen both hit passengers for excess baggage in just about every class & airport I've been through recently.
As Paxboy says, it's more a case of what kind of day the check-in staff have had & how they felt when they started their shift that sets the tone for any leeway you might get.
The best advice I can give is to smile & be nice at check-in, it might just work in your favour....