"Commercial" VagCom- more stuff it can diagnose?

[carrotchomper]

Afternoon all,

Decided to buy myself one of the cheapy eBay cables. Ordered yesterday, arrived today £17 including software and postage.

I've been having a play on the car and it seems to be pretty good, cleared some faults on the central locking, also a fault I knew about on the satnav, but nothing coming up for engine/gearbox.

I have a slight problem ATM whereby the car feels like it is misfiring almost at 30ish MPH. I did think it was the gearbox, so took it to the local specialist who road-tested it and doesn't reckon it is. They indicated that, even though there are no faults on my Vagcom showing, an Audi dealership would have a better interface-

Is there any point shelling out a fortune to plug into Audi's system- I mean, is it going to be able to detect any different faults?

Ta!