KEF R11 / JBL HDI3800 /DALI RUBICON 8/ B&W CM10 S2 / REVEL F208

Those 5 speakers are all you are considering? 
These choices would seem to be mostly widely available. You cannot go demo them? I’m thinking the guy that really liked the JBL would not like the Revel so much and vice versa. 
My rule has always been if I can demo it and love it I will consider buying new. If not buy used at smart prices and you can normally get all your money back then move on and try other things. 

I really like Dali's hybrid tweeter module.  They can sound "bright" on content that is hot in the treble and upper mid range, but on well recorded music, they are very nice sounding.  I heard the Rubicon 6 last year at a dealer, and it was impressive. 

B&W speakers never seem to measure very well, but they have a "house sound" that a lot of people love.

The Revel F208 measures well and has been a top recommendation for a long time now.  This one may avoid the brightness you mentioned that you don't want.

The JBL HDI 3800 may be the most dynamic of your choices.  It's all down to personal choice, so you really need to listen to them yourself.

I just want to make sure I will be avoiding the bright, harsh sound reproduction. There is much contraversy on the brightness of B&W and KEF and lack of reliable reviews on the JBL as it is pretty new. People seem to be happy with DALI and REVEL generally though.

The room is treated acoustically favorable, well, to some degree. I will be driving them with Yamaha AS2200, though I have plans to upgrade to Musical Fidelity M8Xi in the near future. Dual REL S510 will also be in the system. Thank you...

Im using  B&W CM10s for the past 3 years. Ive never needed a sub . Ive never listen to your other selections. Had the upgrade bug for the past 6 months ,Ive auditioned Vandy Treos ,Tannoy turnberrys , B&W 804Ds and Harbeth 3.0 all great speakers , You can pick up a pair of the CM10s for 2500 or less . They are very hard to beat ,but you need good power source 150 watts or more! Good luck in you search,