With your set-up i dont think youll like the Naim; but that will be your decision when you demo.
I personally dont like the Naim sound, more so when partnered with my RS6 speakers. I find the sound too lean and the treble just sounds wrong.
Naim against Arcam is like chalk and cheese. I reckon if you get yourself a quality example of the Arcam Alpha 9P power amp or the Arcam Alpha 10P power amp; you'll be happy 🙂