KEF LS50 or Harbeth P3ESR for desktop system?

As good as the LS50s are, this is a non question. 

The Harbeths are generally agreed to be an improvement upon the legendary LS3/5s. 

Having the Harbeths as part of a desktop system must count as one of life's luxuries. 

It's taken me most of my life, but I have finally come to grips with the idea that I deserve luxuries.  Thanks for pointing that out.

I have not heard Harbeths, but I have had a pair of LS50s for a few years and have used them in a similar setup on my desk. I agree that they will sound better on stands, but I still enjoyed them on my desk. The great thing about the LS50s is that they will fit whatever space you have (generally). I have used them as nearfield monitors on my desk and on stands in larger rooms and they perform well in either scenario.

I just came across a post on Reddit a few days ago with an impressive setup with a pair of LS50s and a small sub in a large room
http://i.imgur.com/sFJ5BUr.jpg

I have also seen them in a setup much like what you’re describing and generally used with a pair of IsoAcoustics stands
https://i.redd.it/jhhyw0xpbxj01.jpg

I would think these show how versatile the LS50s can be.

I've heard the LS50 and Harbeths and found both to be less alive and airy than ATC SCM7 or SCM11.