is there that much of a difference in performance between a Fox RP23 to the RP2?
is the extra 3 worth the extra cash?

and the same goes for XT to SLX is there that much of a difference in performance between these two? (ignoring the brakes)

would going for XT / RP23 justify an extra £500? (difference between two models kitted out with the above)

any opinions / experience on using the above? help appreciated.

No – It’s not worth the extra. Once you get the RP2 dialed in you’ll be in exactly the same place as everyone with an RP23…It’s either ON or OFF. I dont know anyone that changes the settings on an RP23 while out n about.

There was a thread on XT vs SLX recently – the general concensus was that although SLX is slightly heavier it’s also more robust.

Save yourself £500.

depends on the bike.

something like a trance or a lapierre, doesnt even warrent an RP2, just a base R would do fine.

on something dumb/simple 😉 like an orange 5, i think i might want a RP23 (perhaps)
that or an RP2 tuned to the bike, rather than a stock off the shelf one (RP2s that come on bikes are tuned for the frame, for the manafacurers)

not a fan of the SLX brakes, i think i would go for older XT (the calipers look much cleaner), but then the cranks will be hardly different.
is an SLX cassette on an alloy carrier?

In short, i think it depends on specifics.
i wouldnt buy a groupset as a whole, i would (and have) choose parts specifically.

“is an SLX cassette on an alloy carrier?”

yes, albeit a slightly narrower one