Yeah thinking of doing the same. Got the part sat at home, so may as well put it to use.
Conversely, I've had zero issues with VAGs as in design/production flaws. I've never been left stranded by the roadside with the bonnet up and steam pouring out of it. The only time I've had problems were the result of modifications, so self inflicted issues!
Dodgy brake servos only affects a tiny proportion of these cars, hence why only you and I, and perhaps one other person have discussed it if you trawl the forum. The HPFP Cam follower is a sketchy design, but only an issue on modified cars. Rusty wings is absolutely inexcusable in the 21st century, I'll give you that one! Other than that.....just general wear and tear related faults.
By far the biggest problem, in general, with ALL of my German cars over the years - previous owner bodges / cheap skating. The only reason half of them rattled inside was because they'd ripped out panels to fit stupid stereos and not bothered to replace broken clips etc.
Anyway.... you seem like a discerning chap, so this GTI of yours is in for a treat!