We have used CHAS/Equity and General insurance brokers for the last three years and each year we start shopping around at least 3 weeks before. But these buys are always lower.
Our main works is data cabling with security accounting for around 25%, but only in commercial installs as we don't touch residential, unless its an apartment block or student accommodation.
We have the same issue of trying new brokers and them wanting to know what colour socks we wear. That's why we try to get them down to our best quote!
We have 10M employers, 5M public and product, no indemnity as we only design if we install. our T/O is £500K and cost us £500 with insurance.
As some have mentioned you never know how good an insurer is until you make a claim, but I am happy if I never know really how good our insurers are!