Get a 520, and get on strava Iain, I know you say you’re no interested in KOMs n shit, and That’s cool, but….
You can set favourite segments on a 520 and it warns you when it’s approaching, you can set yourself against the KOM, or against your PR, and it tells you how far you are ahead or behind (only really works on road IMO, as I can’t look when I’m pinning a descent!) It’s a great motivation if you like to push it, and the fact you use cadence etc would suggest you like yer numbers on road rides.
Strava is very useful, just gets bad press from the usual whiners.