The KEF Q300 is going for $399 a pair right now, and have no issue with different colored drivers. (The Elac UB5 seemed to come out with some green in the Uni-Fi driver on some shipped.)
I think that would be a good comparison because KEF has about 6 years of making that speaker under their belt now, so it should be as refined as it's going to get.
The most obvious difference between them is that the KEF Q300 is front ported and the Elac UB5 is rear ported. The KEF comes with a hanging bracket on the back, the Elac needs some space from a wall. Depending upon application, the KEF could be put into places the Elac probably shouldn't go. Should be an interesting matchup otherwise.
KEF R500, R200C, R100, R50, SVS SB2000 sub, NAD T758v3 AVR, LG UP875 4K BlueRay, Samsung UN55JU6500F 4K LED TV, KEF M500 headphones, Sony CDP-CE500 CD changer. Office: NAD M10, KEF LS50, KEF Kube 10b, Pro-Ject RPM1 TT w/ Ortofon 2M Red. Guest room: Hafler 300 L-R, KEF Reference Model 100 center, KEF iQ10 surrounds, modded M&K V-90 sub, Bluesound Vault 2.