Loving Davey’s comments!
Yep,ditched my front mech three years ago and haven’t looked back since. I run 32t front and recently went 11-36t at the back. That combination get’s me up most things that I could reasonably expect to pedal up anyway.
Going down, on a 32t front, you will spin out at about 20mph (which would be about 90rpm). It really depends on where and how you ride but personally, around the Peak District, I find that 20mph is more than fast enough for me.
One thing I would recommend is fitting an e13 XCX guide, the one with just the top part rather than a full guide. A full guide introduces a lot of drag into the system and you do notice this on a trail bike.
I’ve tried the MRP 1×9 guide and it’s not great TBH; the backplate is too flexy so if you do drop the chain, rather than it hooking back on, it can force it’s way down between the back plate and the chain ring.