I’ve recently done this. It increased my premium by quite a bit, mainly because the replacement value of my main bike is over 6k.
All others are <2k, so I concentrated on this one. She explained that the ceiling value is 10k – but they will new for old on anything under that.
Which is nice to know, knowing that I would never be able to replace the thing again.
We tried a few ups and downs on excess, with a £200 excess it reduced it a fair bit over what they originally wanted.
I have claimed a few times, with one £5k claim, so I’m not exactly their most favourite customer!
Still worth it however, they were impeccable each time.