we just fitted Polish Rehau system windows to a new house here. Quality of the windows & esp the front door was very good.
Good point about the opening in thing, though, we missed that....it's a problem if you want to fit blinds..............also: they don't fit obscure glass in their bathroom windows as standard, like we do, so don't forget that, either..........damhik !
OTH, I just built a 3600 sq ft house, with 23 opes, from a Mayo co:
2 x french doors
1 x teak front door
21 x windows (one measuring app 1.5m x 4.5m)
Total price, inc VAT & fitting - Eur11k.
All work well. Front ones, incl the large one, are grey, wood-grained PVC, the balance white.