I am in the process of building up my Planet-X XLS CX bike and it came with one of these front mech pulley things to adapt the top pull cable to bottom pull mech. I’ve got a bottom pull mech so would like to use it. Anyone got any experience? Are they straightforward or should I go top pull mech?

they’re straightforward to use but are in just the right place to accumulate a lot of mud, if you’re going to be riding your cross bike in the mud, if you already have a bottom-pull mech then use it

My first MTB had one of those…back in 1992! 😉

The fitting was brazed on, though.