This forum and the NA market in general is heavily Apex slanted, but the Profilux install base by all indications is growing at a steady pace.
@Ditto has an extensive thread on switching, I have switched from a rather large Apex install across two systems,
@Torx made the switch a few years ago. I haven't really kept on others that have switched, but I won't say it was flawless and everything is roses. Overall though I do not regret switching at all, and kind of wish I had done so before a few of my last Apex purchases. My largest overall opinion of having switched, I don't have that urge to "check the dashboard" daily, or even multiple times daily, anymore.
Upon making the switch, I did reconsider how I wanted to control my systems; all eggs in one basket is not what I do now. When I was with Apex, that was my only goal, everything must work with the Apex, etc. For example, my power heads are now on external to Profilux controllers (IC2GC / Wave Engine). While they can be interfaced with a profilux/apex to initiate some specific things (a maintenance mode, feed mode, etc), they do not require said external controller to function. This is a form of controller redundancy, and frankly side?-loading that I chose to do, but that said I am a huge proponent of gyres over all other power heads, so this path made the most sense.
If you're running heavy Vortechs, control of them is still an option, or Tunze, or any other 0-10v input capable pump. Return as well, you are not limited or chasing a "GHL" ready pump. Anything 0-10v works, or just buy an AC pump and never worry about it dying prematurely.
I still Apex is a good controller platform, and the "classic" head unit is still near bulletproof (and I still have my original one on my fathers FW system), but I no longer wished to support the company going forward.