Great cars, I had an R53 JCW with 210bhp before my current Cup.
Parts prices can be steep, my clutch and dual mass flywheel disintegrated at 30,000 miles. Still in warranty but BMW said it was my driving style..... I'm 45 years old and have owned almost 40 cars, never before have I worn a clutch out. Anyway I digress, it cost me over a grand and that was at a reduced rate as good will from BMW, should have been about £2.5k for parts and labour!
Valeo, that make the oem DMF have since made a single piece flywheel due to a high failure rate. Info from Valeo's own website.
I loved mine though, they do handle well and sound out of this world with the supercharger whining.