I did on a nMP 3,7, 64GB, D300
It boots in less than 3 seconds in High Sierra.
I did have problems with the wifi the first day, It would connect but I could not surf the web.
Then it worked sometimes, but Firefox was extremely slow.
After a day or so and having done some reboots.
That problem went away. Other browers are fast too.
But my production machine was/is a cMP 3,1 2,8 8 core, 64GB, 1TB SSD Sata, spinners, USB3, GTX 680 for 4K.
El Capitan
I would not have jumped so quick if the nMP was already loaded with all my apps and stuff.
I prefer a clean install. But I didn't want to install everything again in 3 months.
And High Sierra is interesting for me, as it would make NVME PCIe SSD's bootable.
I'm still setting up the machine and have not yet did some serious work loads.
The apps work.
The OS Itself is annoying compared to Snow Leopard, Mountain Lion, Mavericks, El Capitan imo.
But I got used to that, that every OS get's more kiddy.
But at least It more interesting for SSD's, and TB2/3 workflows ...
Installing is always a risk. Even a .6 version. A .0 version is the biggest risk.
Especially if you have limited recovery options, or other internal/external bootdrives around.
On the cMP, I've always migraited slowly from one boot drive to another with a newer OS.