I swapped my 8088 with a v20 in my system - it was already an 8MHz 8088 so it was faster even without the NEC CPU, but the NEC one was even faster. I don;t recall (or at least it wasn't as readily available) NEC math coprocessor, I had an ordinary Intel 8087.
Digging in a box of old chips (in anti-stat foam), I somehow still have the v20. I don;t think I would have bought 2 of them, and I last used the machine in the mid-90's when I donated it to the model railroad club I belonged to, complete with a couple of programs I wrote to keep track of membership and also manage the small store we ran. Can't imagine I would have swapped the CPU back, but obviously I did. Unless I came across a second v20 later on - I put the v20 and the 8087 in it when I was still in college, probably in '87.
I do remember STB, and particularly AST - one of the companies I worked for, we commonly sold AST servers.