In our rebuild (post-fire), once I decided to go VFD, our plumber put in the Pentek Intellidrive system, driving a Waterfurnace Series 5 (and the rest of the house), and it's been flawless. He also put in a normal pressure gauge so I can see the "real" pressure, and it sits at a constant 58psi no matter what's happening inside, with maybe a 1/2psi fluctuation under load (ie, furnace and a tap or two).
Originally I wasn't going to, but decided the old well pump (Grundfos), while working fine pre-fire, was approaching 10 years old, and I didn't want the risk or failure. So we got a new pump plus the Intellidrive. And it turns out during the install that the pitless adapter at the well was cracked (10ft underground!), which we'd never have found if I hadn't gone for a replacement. So the builder had to dig it out and replace it (amazingly, at no extra cost to me).
I think the whole kit'n'kaboodle was around $4k (installed), but I consider it money well spent.