Personally i did try the cheapo at 1st & then learned my lesson & bought authentic full hex can usb which I wish I did 1st of all so I totally agree, all these people that have a 20k car & actually some I've actually convinced with new 30k s3's or a3's complain about £230+ for the lead but they happily pay audi £100+ an hour for work, get real, if you can afford a nice car of even 10k upwards you can easily afford the genuine item & also you get the benefits that come along with it, full access to all modules, free support, free updates, use on all vag cars(unless microcan)
For all those that want to get vagcom cheap, dont be so tight/cheap, if you are happy to cough up money for maps, exhausts etc all costing thousands overall then something that can save you thousands literally as it has me & convenience factor along with not having to pay the stealers so much, tell me why you wont pay for the genuine???
As for not using all the functions, like what exactly as if your car hasnt got all the systems installed then of course you cant access them all, just cause vagcom has all those modules doesnt mean your car has them all, common sense prevails I would have thought & your car is canbus given its 03 onwards, my old S4 B6 avant was 03 & was canbus so yours will be, even the S3 facelift 8L from 00/01 was canbus so yours must be, but canbus has no relevance to what you can access at all on your car, its software related or whats actually installed on your car.