I've never had an issue with mine, and used it on various cars. I'm sure Mark and Lee both have ebay cables and craig has one too without any problems.
The only connectivity advantage the rosstech cable gives you is that its a native USB interface. The ebay cables are serial, but use a USB to Serial convertor, and in some cases the port number the PC allocates to the convertor changes, usually when you use a different physical USB port on the PC.
IMO its not worth double the price, for a B5 anyway, however if you feel its worth the expense then go for it. At least with the real cable you'll have support from rosstech for the hardware too.
