Center channel matched with Fronts??

I would say that if you feel the speaker is too forward now and you leave the center and replace the L&R fronts.
Make sure you buy a model of speaker that offers a matching center, because you will be back to get it later.
A forward sounding center speaker that doesn't voice/timbre match with the LR's will be in your face. I also agree match the rears, expecially when listening to a DTS soundtrack. All MHO

I had the pretty much the same speaker setup and thoughts as you (Monitor Audio Silvers and matching Silver Center). I thought the MA center was very nice for theater/tv, but hated the silver 8's because they were too forward/bright. I contemplated keeping the center, but sold it off as well when I picked up some quad 22L2's. That said, the Quad center is smaller (smaller 5 1/2" drivers I believe, compared to 6 1/2" drivers in the MA center). You can do quite a bit to help fill out the center channel sound by properly adjusting speaker crossover settings along with the subwoofer.

I set my 22L2's to "Large" on my processor, the quad center to small (crossed over at 70hz or so). This essentially pushes everything on the center channel below 70hz to the sub and lets the L/R channels go full. I use a fuller sounding IC to help beef up the center channel sound (I went with a single Cardas Golden Cross RCA). Then tailor the sub output to just fill in enough low end response so voices sound full/natural (making sure it's not crossed over below 70hz or you'll have a gap).

I'm running 200 watts per channel to the center/surrounds via a Sunfire amp and 250 watts to the L/R via an MF integrated. Key thing is having enough power, particularly if you're not crossing over your main L/R speakers below 70-80hz, otherwise it may sound thin.

As for rear surround, maybe I'm not as picky but I just went with a cheap pair of paradigm bookshelf spkrs. As long as the amp is beefy enough and the pre/pro is decent, I've always thought any good rear surround speaker will do for me.

I think the advice given by steuspeed is correct;if you can't match as in my case I was advised to run center channel as phantom; I did until I could buy a matching speaker.

You can easily get away with a well thought out non-matched center, while there is ofocurse a benefit to a matched model a bit of snob kicks in when people are asked about all matched speakers, mine match as of now but I have had excellent results in the past when older speakers simply didnt come with center options or budget kept a matched center from being possible.
I would choose a carefully thought out non matched center over phantom anyday of the week, if folks sit off axis its not going to work great and even on axis sometimes center info is hard to hear..........the center channel is there for a reason, its not just hype. Match all if you can, if you cant from center to rears just audition and you will be happy.......its not as cut and dry critical as many would make you believe and your ears will confirm this!

I bought the RS6 for front L&R and feel they are brighter than I want. I have not bought the rest of the home theater speakers yet. Was thinking of getting the center in either the RS or the Radius 180. Would either work or must I have the silver RS center? For rear speakers I wanted to get something warmer sounding to, hopefully, warm up the general sound. I can't return the RS6's so must keep then for the time being. Was looking at Quad, Dynaudio, PSB, and Era bookshelves in the less expensive lines for my rear speakers. What are some recommendations for warm, smooth speakers and do you think that by having warmer rear speakers, it will warm up the sound and balance out the brightness of the MA RS 6's?