Blimey, you didn't keep that one for long!
I'm not sure how much a Cat D makes a difference to the price of a bike of this age, especially as it happened 10+ years ago. Most bikers looking at bikes like this know that cosmetic write-offs are not uncommon and you often end up with a better bike because of it: more work has gone into it and lots of new parts have gone on.
Personally I think you could have asked for more.