The results were mixed - they either work really well, or really badly. It seems that the home's wiring and appliances have an overwhelming effect on their efficacy. So, the recommendation is try before you buy if at all possible.
We recently just got a Netgear Orbi and are pretty well satisfied. Turns out the base router/AP is better overall than the other single unit devices we've been using until now and the satellite does seem to make a significant difference in the far top floor room which had problems with both WiFi & Powerline. Lucky for that, too.... our next step was to run cable in the walls.
The Orbi is basically the wireless equivalent of running wires through the walls.
You can have a mesh network without wireless clients at all if you wanted. For example, you can connect two locations together via a mesh of access points by each end plugging into the ethernet port of an AP, then the mesh provides multi-task redundancy.
Having said that, we had reached the point where I was about to call cabling guys to come in and just get it over with... which would have been some multiple of the Orbi number. We had also had various range extenders and bridges, etc. over the years and frankly I wasn't expecting much of the Orbi either.... but we've been pleasantly surprised with how well it's worked. The only complaint I have is that it does seem its configuration UI (web based) is rather sluggish at times... but I rarely use that.
At this point I think I can fairly say that for us it's been worth the price.