| I replaced my rear sprocket with a Renthal carrier and 40T sprocket. I also have a bit of lateral movement along the axle. Asked about it come service time and was told it wasn't an issue (I also raised the point during the MOT - it only becomes an issue if the cush drives wear enough to foul the swingarm).
The bike has done 4k miles with the sprocket and never had any problems with it.
Hope this helps | 
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