I know it's been a while since you posted, but I wanted to share my experience so far.
I got my chip to run stable at 4.7GHz all core at 1.29375V with max temps of 60C(die) and 72C(CCX) on an Asus Strix x570 Gaming-e. During my tests, I managed to get it to 4.775GHz all core at 1.3675V, but never 4.8GHz...
Regarding the benefits of overclocking, I believe there are many, depending on your workload. Firstly, fluctuating clocks and power states create a lot of latency, especially on multithreaded workloads. Secondly, you can achieve higher than advertised clocks using much less voltage, resulting in lower temps and lower noise levels.
PBO might give you higher clock spikes on a few cores and get higher scores on short single threaded applications and older games, but it pushes much higher voltages (my x5600 pushes over 1,43V to get one or two cores to 4.85GHz) and consequently much higher temps; which, in turn, will result in lower overall clocks on sustained heavy applications.
My point is, PBO is great if you want a convenient way of getting a little boost on performance, but the level of control over temps (fan noise) and performance you get with manual overclocking is much better.