I think I also installed a Gates kit or two in the past. No issues I remember either. Gates is a reputable supplier so I am sure any components they source from other outlets for their kits are also fine. I think I remember seeing INA idler bearings (good). Can't remember what WP, but as long as it has a good cast steel impeller, I doubt you can go wrong with it.
A partial list of known good belt manufacturers we have seen happy results from, whose kits would probably be trustworthy also: Roulunds (original supplier to Volvo), Ruville, Gates, Dayco, Continental/Febi. In no particular order.
As ngoma said, the real issue folks sometimes run into is not with the parts themselves but with how they are installed. Correct torques, timing, tension are the keys to success [or failure], achieved only by carefully following proper process and specifications, using the right special tools and methods. None of it is rocket science, all very easily accomplished as long as one is not tempted to attempt shortcuts. As you probably already know from your past experience.
If you have a 5cyl 2.5 TDI in a van it will all feel very familiar, highly similar engine design and belt procedure, but with much easier access for working in the Volvo bay versus in the van nose. The only difference is the use of the water pump to adjust belt tension. Some of the old 5cyls had that too. Sounds like you are well on the right path already to doing it right.