Thanks for your replies everyone. Yes, they do seem good to deal with, but the reason I asked about claims handling was because I'm currently with Pantaenius so in changing I'm moving from an insurer with a good reputation for handling claims. So I just wanted a bit more info.
It's just the nature of insurance that you can be perfectly happy with the service when you never need them.
A neighboring yacht had some damage caused by someone running into him whilst moored up on a pontoon. He is insured with Pantaenius and was not best pleased when they started to quibble about his £800 claim. He worked out that he had paid them over £50,000 in premiums over the years without making any prior claims. He was not a happy customer!