Yeah, very good points about the remap and insurance. Having said that, selling mine and replacing it with something faster would be a lot more expensive than the extra insurance.
Warranty definitely worries me though, especially as I've just forked out £400 quid for one - it would be really annoying if, after paying that they refused to cover something because they found the remap.
Most I've got out of mine is about 510 miles. It was quite handy over the recent fuel shortage not to have to fill up. I did a whole week's holiday, driving from London to Suffolk on that one tank.