I have found a new 2010 XTR crankset for £280 but is it worth it? for the extra £120 for a XT off CRC I seam to save 100g, allegedly it is stiffer (ohh er!) and I believe the middle ring is Ti which I also believe will last longer. Any other benefits?

Yes definitely worth the extra, I have full xt on one bike and full xtr on the other and I can tell the positive difference every time I ride. Also the xtr chainrings, crank arms and cassette are about twice as old and still in better condition. In my opinion xtr is well worth the extra.

Everyone will swoon in the car park when they see how rad you kit is 😉
It’s not worth (IMHO) talking VFM once you get past SLX, I mean the deore kit is the best VFM without a doubt, and very few ppl will notice your cranks once you start cycling. That’s not a criticism of XT or XTR & not to say dont buy it, just dont talk VFM with today’s prices (silly compared to 4/5 years back), you either want it enough to buy it or you don’t.
As a side note take a look at rosebike.co.UK for some pretty damned good prices

No chance! It looks nice and is a touch lighter. Fwiw I have those exact cranks though I got the cheap and second hand. Save your £120 for something more worthwhile.

Head says it probably is not needed, heart says buy it. Damn you shiny shiny syndrome!

Go for it, I had the same choice a little while ago, xt for £135 or xtr for £275. Chose xtr, just a little bit nicer in every way.

the voice in your head will always say you should have bought it, if you can afford it then why not?

i picked up a M985 Race chainset for £250 from German eBay – at my door in 3 days,

Have a look at the cost of replacement chain rings, that may influence your decision of course other chain rings are available but if you want to keep it XTR in the long term it’s expensive.

I swapped 2009 XT for an old XTR M960 crank. The difference in stiffness was amazing, it felt the same as taking your winter muds off and putting your summer tyres on. Well worth it I think.

Buy it cos if you buy the XT you’ll still want the XTR

Waste of money IMO.