I've had 107/2s since the early nineties (replaced my AR9s). I think the differences between the 107 & 107/2 is mostly attributable the KUBEs each use. I listened to both versions when I was shopping (the dealer had older ones still in stock), and I recall thinking the /2 was worth the price difference (around $500, IIRC). KEF claimed the only changes were a new tweeter, bi-amp ability, and the design of the KUBE... my suspicion then, as now, is that the KUBE makes the biggest difference. I listened to each, with, and without their KUBEs, and the older model sounded worse in the mids & highs, with the KUBE. The newer model sounded almost exactly the same with, or without it's KUBE... except for the improved base, of course. I wouldn't use my 107/2s without the KUBE, if I had an older model, I'd look for a newer KUBE!
Also, it should be mentioned that any 107s are going to need new woofer surrounds by now, even the last of them are certainly cracking. I just redid mine a few weeks ago, and I should have done it a couple of years ago! A properly working pair of 107s (with the KUBE) have AMAZING base that IMHO can't be beat for less than $10k.