Performance is indeed great at the moment. I'm on S1. When it comes to front-end cached pages, I was averaging around 650 ms prior to the processor upgrade, now it's around 500 ms. WP-admin feels a bit more responsive, too.
As for NVMe, I had the chance to test the performance of a friend's site which is hosted on a server located in Germany which had NVMe SSDs, and it was indeed quite a bit faster there vs. the previous host. Avg. load time of cached pages went from around 450 ms to 220 ms for that site, with everything else being the same (LSCache enabled). But I also heard that NVMe servers cost up to 4-5x more in the US than in countries like Germany, and perhaps that's why I'm yet to hear about any US-based shared hosting server of any provider being powered by NVMe storage.
About this processor upgrade, how big of an upgrade was it in terms of processor architecture? (i.e. Intel 4th gen. vs. 8th gen.) Clock speed hardly tells the whole story, as efficiency goes up every year. So, even though the newer processors are clocked 21% higher, I think the actual performance gain will be much more than that.