How many miles on your car...and how many chipped?
The improvements depend on how bad your stock valve was. It deteriorates slowly, and the effects are subtle over time. I had 15K on my car (13K chipped), and I replaced it. I noticed that acceleration after shifting seemed a little better (less delay before I would feel the turbo again), but the most appreciable difference was that acceleration was smoother under high boost conditions (low rpms, and heavy throttle). There wasn't a distinct impression of more power, rather a lack of "fluttering". In addition, 1st gear acceleration was lumpy. A throttle adaptation with a VAG tool would fix the problem, but within three weeks there was some maladaptation and the acceleration went lumpy again. The BPV cured that, which was the main reason I upgraded the part.
If your car seems to drive smoothly, wait until you notice it failing, and then replace it. The installation is eash and should take about 30 minutes. You have to access it from underneath (remove the splash shield as if you were changing the oil). I can't give you more specifics since I didn't do it myself.
TAP, Forge, Bailey and PES seem to be the main players here. Any one of them should do just fine.