I think the RENTHAL one is the best that you can buy, I ended up buying the MPL carrier and sprocket as I got it for a good price. Had it on my 996R for year and half now, I have no complaints and are extremely happy with it, as with all the MPL stuff it is well made.
the mpl ones are good value for money in terms of quality etc but they dont have the little cush drive supports, which for me are essential, if you have ever had a cush drive start backing out and eating up your hub like i have you will know its nasty, swarf evrywhere!!
so get one with these is my advice.
the renthal ones are good but i dont believe that they have the phosper bronze bush in the middle, not sure if you need it mind? but i guess its to deter corrosion
i have some sprocket carriers that feature the cush supports and the phosper bronze bush. if you want one u2u / pm me for details
I've got an STM one fitted, which has the bush and steps to stop the cush drives backing out. Whichever one you get, make sure you can get hold of sprockets to fit it at the right price, as they're not all interchangeable. Cheers, Pete
The stock rear sprocket incorporates the cush drives etc. What Renthal do is replace the centre, where the cush drives sit, with a separate unit which you then bolt the sprockets to. Initially it costs you more, but once you've got the carrier the sprockets are about a 1/3 of the price of OE sprockets and you have a far wider range of sizes to choose from. Another benefit is that most of the carriers have a retaining lip to prevent the cush drives backing out and mullering your hub casting. IMO, the Renthal are the best in terms of quality, price and also maintaining good chain alignment. All the carriers i've seen use either 520 or 525 on the same unit. Some don't give good chain alignment depending on which size you have fitted, which sjows up as heavy wearing to one side of the sprocket.