I personally have Barnett/EBC Carbon Fiber clutch packs with steel discs in all my bikes and love them. For example, my 12 Y/O daughters Yamaha YFZ450 went through the stock clutch in one year. The Carbon setup in hers is going on two years with minimal slack adjustment to compensate for wear. And talk about no fade great grab starts? No comparison.
For my 2-strokes I use only Pro-Honda HP Trans Oil SAE 80W/85W. Sorry about the red wing, but I do have a CR500 and this oil is by far my only choice for tranny/clutch, even in my KX and RM.
If your bike is stock and do mostly trail riding with little clutching or lugging, stock clutch is more than fine. My KX5 runs a modded motor in the sand and the stock clutch won't hold up to the power transfer of a paddle tire. The clutch is the weak link in the power to the ground ratio and the better the pack, the better the power. You have aluminum discs in your bike?? Toss out the setup and get carbon with steel discs and you will never complain of slippage or silvery gear oil again.
Cost got you worried?? If you put the hurt on the clutch because of riding style or motor mods then think of it this way... Barnett/EBC for $120 and lasts 3 seasons or a low end/stock set for $40 and change every season? Works out the same but performance/fade is much better. Put three heavier springs (either the mediums or heavys) in the with three stock. Clutch pull can be setup pretty good with the alternating of the stock, medium, and heavy springs in groups of three in offset pattern.
Lots of people don't realise how much their clutch is slipping (losing power) or shifting crappy (hot plates on hot discs with cheap oil).
Sly