When it comes to pure gaming performance, the Ryzen 5 3600 outclasses the Ryzen 7 2700.
The ROG Crosshair VI Hero is basically a starship compared to an X470 Prime Pro. In fact, my X370 Prime Pro actually outperforms that one because they nerfed the heatsink design on the newer model.
Regarding the motherboard, I'm convinced there's nothing better out there—and there likely won't be for $333. Once the official ABBA BIOS drops (which is just a matter of time), we'll be all set.
By the way, voltage spikes hitting 1.5V are completely standard behavior for Ryzen 3000 series chips.
It is perfectly okay if your CPU is periodically using 1.4-1.5V to achieve boost frequencies, and you should see dips into sub-1.0V as the CPU goes into idle. These dips may be brief, and that's okay. Load voltages of around 1.2-1.3V are perfectly okay also. This is the processor working as expected. Ryzen is a highly dynamic system, with up to 1000 voltage and clockspeed changes every second. You will see a lot of bouncing around as you work with your system.
I anticipate that many people are now trying Ryzen processors for the first time (because they're awesome), and may not understand what to expect versus whatever CPU they had previously. You want to know if what you're seeing is "normal," but may not know what "normal" looks like. I get it! I want to assure you that the CPU needs voltages to boost, and voltages of 1.2-1.5V are perfectly ordinary for Ryzen under load conditions (games, apps, whatever). Even at the desktop, Windows background tasks need love too! You'll see the CPU reach boost clocks and voltages, too.
As for the other Navi GPUs, we might be waiting a while (check TechCrunch for updates). Because demand for 7nm is so massive right now, the 16-core version is likely delayed, and the rest of the Navi lineup and Threadrippers probably won't arrive anytime soon for that exact same reason.