I don't have a Clare, but I have a Vintage from ICC and it's been great (and I expect the Clare is too).
I started on a Swan from McNeela and played it for about 6 months, but it quickly became a limiting factor (one of the keys was damaged on arrival and I had to manually repair it, the action was generally "sticky", and the bellows was restrictive). My plan was to start on a Swan and take advantage of McNeela's trade-in policy, but when I contacted them about it they told me that they'd only give me about 30% of the Swan's MSRP as trade-in value toward an upgrade (which surprised me, since concertinaconnection promises 100% of the MSRP when trading-in to an upgrade). So, that was kind of an unpleasant experience and it soured me on McNeela ever since.
In contrast, the Vintage from ICC is really responsive and has an incredible bellows (and I believe the Clare and Vintage are similar in those respects). My one nit with the Vintage is that the very lowest reed tends to go a few cents flat when played loudly, but that seems like more of a property of the choice of reed material rather than the concertina construction itself. In fact, the Clare may not have this problem, since it uses accordion reeds instead.