Why is there a reduction in lifespan? It's lighter than XTR, without the softer ti sprockets, so should last longer (unless you live in the alu 42t, in which case you bought the wrong chain ring). On what grounds should it be less than £100? 
My XX1 is doing far better than the XTR that preceded it.
RRP is pretty irrelevant too, who pays RRP?
Generally I'm a Shimano fan though, well impressed with the new XTR mech and shifters. Personal though at the end of the day.