I am looking to upgrade my system and considering these speakers:

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

I will be pairing them with REL S510 subs, probably going dual on them. I know some are new speakers on my shortlist but I would appreciate your input in terms of how bright they can be. I would rather go for neutral-sounding speakers without any harsh/fatiguing listening experience.

I just listen to music.No HT setup whatsoever.
Thank you guys
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...
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.
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.