I've never had an issue with Cornmarket, although yes you do have to do a bit of legwork every year but they have always matched like for like if I have found a cheaper policy. They also provide class 1 business cover (or something like that) for no additional cost of you are an IAM member.
The main issue that this post is highlighting is that they told me something verbally on the phone which was not true, which I only established by asking for proof in writing from the underwriter. Whilst in the scheme of things this may have just been an innocent oversight and unlikely to cause me an issue, what would have happened if someone had had an accident on the bike and injured themselves or others and hadn't insured it. An example here : https://www.whitedalton.co.uk/motorbike-blog/2013/10/i-sold-my-bike-but-didnt-cancel-my-insurance/
RBW.
Classic example of a call centre chimp saying something they shouldn't