Based on some of the comments I might assume that not everyone is familiar with the intricacies of under-volting, which is part of the equation with PBO2. I know someone that used it to good effect on Zen, so perhaps Zen 3 will benefit from it as well. But because of the changes in Zen 2/3, it must be dynamically modulated to get a benefit (for Zen 3). Just a guess, but I would wait for independent reviews on PBO2 / new AGESA before passing judgement.
Also, I understood the new AGESA would be required to assist with DDR4-4000 1:1 stability, for those marginally capable, but could not do it on the current AGESA. Just more knobs to twist and levers to pull, which is all good.
And yes, < 2% performance improvement is hardly noteworthy, which is why I found the 3000XT variants questionable, but those were a different SKU/price, which is not the case here.