I've heard negative things about all the popular tuning companies. I mix with a lot of people who drive different marques from the vw group. Everyone has their favourite or their reason to change software for what ever reason.
For some it's how the car performs afterwards, some have major issues and they get swept off by the
dealer/file producers where as others will endeavour to rectify these issues.
I've no doubt that mr Gower knows exactly what he's doing, I'm a fan. I follow him on Facebook and I really like his TiV map strategy
BUT I've flashed over more if his files than any from any other tuner. Not a lot mind but the people who had already a) travelled all that way to him and b) paid good money were not happy for one or a number of reasons, so they switched. That's not just limited to Revo I've known people swap to APR GIAG and other custom tuners files too.