What centre channel are you using?

No center only really works ok if 1) your processor supports a phantom center and 2) if your sitting pretty much directly centered.  Otherwise your guests are getting the short end of the audio stick...

back to the op:. I just "side graded" my old Martin Logan Ascents/Logos center to a trio of Gallo Strada 2's and a pair of Gallo TR-3D subs and couldn't be happier.  (A request was made of me, to reduce the speaker footprint from the ML monoliths to something smaller) The Logos was "kinda" timbre "close" to the Ascents, but nothing is better then three perfectly matched fronts.  Awesome.

I'm trying a KEF LS50 for center with KEF Reference 107/2s front LR and LS50s side and rear surrounds.  A round of pink noise reveals the LS50s match the big 107/2s well, and the sound for music and HT is superb.

i am a fan of full range speakers for centers. I use Klipsch KG5.5 for my center speakers behind an AT screen. 

My 2/4/16 post needs an update.  Although pink noise suggested the KEF LS50 would be a good match with the KEF Reference 107/2s, I was always aware of the LS50 as a separate speaker.  The KEF R600C blends seamlessly with the 107/2s.  I do use four LS50s as surrounds.

LM-1C DIY Speaker.

Extremely clear, matches my much more expensive side speakers superbly. Very flat response. Tweeter is very highly thought of, woofer or it’s variants is being used in several boutique speakers. Listener needs to be between tweeter and woofers for best sound.  Compared to a lot of audiophile speakers it may be too flat and maybe even a little dark, but perfect for movie and dialogue.

The design is free (as in beer), parts available from various sources. I have no financial interest in whether you build one or not. :)

Erik