What's your application? When I wrote a ray tracer that did photon mapping, I needed about 300 000 000 random numbers per light to get half-decent results. Admittedly, I could have done more to optimize my use of those numbers, but the point remains that you need huge numbers of random samples.

I used mt19937 for this and it worked ok. I suspect that using pcg might have shaved a few percentage points off the total run time of the program (maybe I should do a benchmark sometime). If so, not a huge win, but noticeable. Especially if you're doing renders on a larger scale than I was. A couple percentage points could trim a few computers from a render farm.