They are a major upgrade IMO. The outside edge of the ring is beveled and the bolt heads are recessed on the M-31. The M-31 also has washout holes in the ring. Not so on the M-21 and the reason I will probably swap. Ripped bolts out on one M-21 in Nov and had to repair the wheel. Ripped a ring and broke it on last ride....
how well has your 1000 held up being these are 0mm offset, have you broke anything due to wheel or have your ball joints/a-arms/axels worn out quicker or been upgraded to handle stress