TBH, you can have issues with any tuner...I know from personal experience in the past.
The larger tuner have extensive development invested in their product, but that isn't to say that smaller tuning companies can't be just as good.
Sometimes, yes, othertimes not true. There are two certain 'tuners' (one beginging with 'S', and the other begining with 'C') who are undobtedly 'large' - but unfortunately - they are actually way too large to offer any real, dedicated VAG in-depth R&D when it comes to remaps - and this has been proven on numerous occasions.
OK, it is well known that Revo could also be classed as a 'large company' - but the beauty about Revo is that they mainly dedicate their R&D soley on VAG marques. But just because someone like, say, R-Tech may
appear to be a 'small' company - what is absolutely clear is that they too are dedicated to the VAG marques too (OK, they also do Fiat and BMW - but I don't think they spread their wings no where near as wide as some of the other 'large tuners'). They also have some very tasty 4WD rolling roads - which are very rare, and are not found say in Portsmouth!

The thing is people will always recommend from personal experience and recommendations of satisfied customers..that's just the way it is. If you find a tuner you are happy with, all the better, you just have to have faith that they are as good as they purport to be and don't have hidden software glitches in their maps that could ultimately damage the car. 
OK, two issues. Firstly, yes, I basically agree with what you say, and recommendations can indeed be very important.
But my second, and more crucial concern actually addresses certain 'individuals' who state these recommendations. Some of these may actually be - well - dare I say it - more than a little gullible - and wouldn't actually know the truth even if someone was BSing them. These types can actually recommend a product or service, when they personally
believe it is good. However, when alternative POV come to light, these same peeps seem to have great difficulty in shifting their own opinion - and adamantly continue to 'recommend' even after conflicting evidence is bought to light!