in other words, an xtr rotor is fine with an xt brake, aye?

Aye. no bother.

cheers!

You can go further and mix brands, too. Pretty much any combo works except for a few floating rotors where the rivets rub.

and even then it’s worth fettling; I’ve a set of Hope floating and Shim calipers

70% interchangeable however some have deeper braking surfaces etc for certain brakes so some are not.

cool, so gonny buy:

xt brake,
http://www.merlincycles.com/bike-shop/mtb-parts/brakes/disc-brakes/shimano-disc-brakes/shimano-xt-m780-disc-brake-sale.html
£64.99
xtr rotor
http://www.wiggle.co.uk/shimano-xtr-centre-lock-203mm-disc-rotor
£40.49

is there a point in getting the more expensive rotor, does it work any better than a standard £15 one?

This is to replace the front brake that came with my genesis, bog standard shimano, never been happy with it, any advice before I buy?

ps, I need centre-lock.

Some systems need a certain thickness of rotor.

I’ve never found that expensive rotors make that much difference , buy an Avid G2/3 If your an every day rider . If your Aaron Gwin It may be different.

No you will die….