I have to say my experience of arranging PI insurance through the BKN provider (Arlington) has been extremely good.
I decided to seek an alternative quote on my last day of cover and they were personable, efficient and - icing in the cake - they came in with better cover at a better price than my original.
Just my unbiased opinion. I used to work for a **very** big broker organisation and I know what their real job should be. It was refreshing once more to see a broker who is working for the client, not the underwriter, and taking trouble to get the best cover for the little guy's needs.