dissapointed - new LS50w's vs old PioneerFS52's/Luxman R113 - so far Kef's not so great?

The problem with kefs is that they’re kefs. Over rated and over hyped. I would go insane listening to them through the break in period. So much that I would have to sell them before they would get there. 

Unless the 'W' above is a mistake, the OP has the wireless version of the LS50's with built-in amplification, so I don't think the problem is lack of power. 

Personally, I lived with the original, passive LS50's for a year or so, upgraded virtually everything else in my system and added quite a bit of sound absorption to my room, but could never get rid of an edginess that was ultimately unacceptable to me.  Traded them in for more mellifluous speakers (Alta Audio Rhea's) and all was well.  They really should have decent bass, though, down to 40 Hz or so.  I suppose it depends on what level of low bass is necessary for your tastes. 

Some folks really do love them, though. Like John Darko:
https://darko.audio/2016/12/kef-ls50-wireless-review-dars-product-of-the-year-2016/
Have you tried the room correction/DSP?

+1 twoleftears   I really don't get this speaker and I've owned KEFs in the past.  They sound like they are out of phase to me and I've heard them with real power in a decent room.  Not familiar with the W ones.

The ls50s do what they do very well (very lifelike detail and coherency) but are small and thereby necessarily limited. Not designed for larger rooms. Yes they also require some muscle to be driven well. They will not shine otherwise and will likely sound downright underwhelming in larger rooms. Even in a smaller room a sub is needed for bass extension. I suspect many have bought these based on the deserved rave reviews and but with unrealistic expectations.

Have not heard those Pioneers but they are larger and likely not as challenging to drive so would not surprise me if they perform well with lesser amps but I would expect a much different sound that some might prefer especially in a larger room.

Apples and oranges are hard to compare.

may be GIGO.... you didn’t name your source solution. I ran the wired version of the LS50’s and found them quite resolving but if your source detail is mediocre you wont hear what you paid for. They are picky about room placement for bass because they are a ported speaker and won't please a bass head because the driver is too small for bass drum and fender guitar bass playback