I have a pair of the Reference 103/3's from the Raymond Cooke era. Although I've owned them for about 17 years, they still put a smile on my face.

I have no current desire to part with them.
Although music used to be my primary source, it is now almost exclusively HT. I'm looking for a possible candidate for a center speaker and was wondering if anyone has successfully paired an older, non Uni-Q KEF Reference speaker with another make/model. The one caveat is that my budget is $500 - $600 tops.
Here's a few speakers I'm considering:
#1 Another 103/3. An obvious choice, but I'd need to get another amp so that I can use the required KUBE (I'll spare you the details

). Plus I'm running a front projection setup and using an upright speaker poses setup issues.
#2 A newer KEF center like the iQ6C. As long as the newer KEFs have the same neutral, uncolored, laid-back-yet-dynamic qualities of their predecessors, it may work.
#3 Axiom VP150. Probably not the best match (Axioms appear brighter than the KEFs), but my surround speakers are Axioms (QS8's) and that would mean if I replace the KEFs with Axiom mains down the road, I'd have a timbre matched 5 speaker setup.
#4 Onix Rocket RSC200. Again, probably not the best match, but it has gotten many accolades and opens the door to replacing the KEFs down the road with Rocket mains (surrounds would still be Axiom however).
#5 B&W ????? - don't have any particular model in mind, but they are similar in kind to KEF.
Any suggestions from anyone would be much appreciated. If you have experience with both the pre Uni-Q KEFs and the current line, or if you've got a synergistic combo of older KEF Reference and another speaker for the L-C-R, I'd love to hear about it.
Jeff