There isn't any delay that I've noticed from a normal standing start. Goes like stink. I'm no expert on launch control but my mate who has an S3 always comments how quick you think it is without launching but when you do launch it seems much quicker. This of course could be imagined as the extra noise and excitement when you launch might make it seem quicker than it is, although 4.8 seconds to 60 is ****** quick.
@DrEskimo - Audi are quoting in their brochures, 3/10sec quicker 0-62mph for the FL S3 saloon over the pre-FL
I would imagine this is down to the extra cog in the gearbox and Audi playing around with the gearing as a result
Just coming from a M135i auto to an S3. The M135i has launch control. Don't be misled, it's no more than a gimmick and a faff to use, certainly not a basis for your decision. Sport auto mode in the BMW and floor it - standing 1/4 at Santa Pod in an unmodified car in 13s dead. Runs tried by others using the launch control were far slower.
The two cars are as quick as one another, it just comes down to the package you prefer after a decent test drive in the end.