Revox B250 quality

I have a Revox B250-S integrated amplifier at home and enjoy it very much. The speakers I use are the Acoustic Research AR3A Improved and this combo is particularly nice when listening to jazz and classical music.
Would I get a significant upgrade in sound quality when buying, for example, a Hegel H360, Rega Elicit-R or Naim Supernait 2 amplifier?

If you have suggestions, please comment!
Sounds like your pretty happy with the ReVox.  There is no real answer to your question, because only you will know if you prefer the sound of another amp over the ReVox.  

I do feel your pain though.  I went through years of listening and collecting gear, some very high end, much of it vintage.  To my surprise I have found that I like the sound of vintage Sansui, and so regardless of what anyone thinks its what I enjoy listening too.

Having owned ReVox tape decks, I can attest to their fine build quality of which I am sure your amp is likewise assembled.  Enjoy your system, it's a fine one.  Put your cash into more music.