What's the differences between the two specs for shifters and derailleuer .??
Is it just weight or any other significant difference ?
I've wondered similar before, as I broke an x4 rear derailleur.
If you Google X5 vs x7 or x7 vs x9 etc. It returns a fair few results.
What I could gather is each higher level you go you get slight improvements in materials/function.
Be aware of second hand though, as a brand new x5 might well be as good as an older model x7 from years ago as they seem to trickle down the certain features when they revise models and something new comes in at the top end.
For what it's worth I went with a new x7 rear mech in the end, which works well, certainly better than the x4 in a number of ways shifts smoother, was easier to set up etc.
Just to add though, I'd view x5 as a minimum if you're on a budget, x4 isn't worth bothering with unless it's standard kit on the bike and it's not broken.
X7 has Clutch mech which isn't available on X5,if your going 1x10 then X7 with Nw
I don't think the 9 speed x7 has clutch, think it's the ten speed model.. Confusing product line up lol