Well I received my Planet Waves NS Classical Capo in the mail a couple of days ago and I have to say its great.
I'm now able to play buzz free without having to take the capo off a million times and adjusting it slightly. The best thing about it is you put it on the desired fret and then simply adjust the dial on the side until any buzzes are gone. Of course you then need to retune, but at least I'm only doing that once now.
Moving it to another fret takes longer, so it's probably not a solution for anyone one who gigs regularly, unless they're good at talking at the same time.

But for my purposes...ahhhhhhh, sigh - much better.
I think my strings have settled too. The change each time I pick up my guitar is significantly less now. I don't think the capo itself is stretching the strings as i tighten it (which I think was happening before to some extent). But, I'm still happy with the ability to adjust the pressure of the capo while it's on the guitar. It's nice and compact too.
I'm so glad I don't need to take my beautiful classical to the doctor. It's sounding very sweet again.
See Dermot, NOT broken!
Report over.
Thanks to everyone who participated in this thread for all of your advice and observations. I'll still need to de-buzz my steel-string, which I think is a completely different issue (and thankfully only very intermittent).
Happy playing. Now back to River Man.

or should that be
M.