The gearing question is separate to the handling one. A little less weight is always a bonus! The nine speed kit I have is getting on a bit and I won’t be able to replace it like for like, so I have to make the jump to 10 or 11 speed at some point. I’m not sure which.
Wheels do need looking at- I’m still running inner tubes (remember them!) so going tubeless is the next step. I just want the bike to be a little more nimble and flickable.