I had my golf 140 custom mapped 4 years ago and have done 30000+ miles without any problems. Well except tyre wear which I couldnt help

Find a local company who will look after you.REVO dealers will offer a 7 day map which you try before you buy. This gives you time to try the map before you decide on what you want to do.
Regarding the clutch/dmf as long as you tell the tuners your concerns about the new parts they will put your mind at rest
Let us know what you decide
ps Dont forget google is best