It's not pointless Iain, it is however not a long term solution. I did over 20,000 more miles on my R380 by going to the cross drilled gear and using the unworn section of splines that existed in mine. The splines had started breaking away completely before I swapped the gear, when I finally changed the gearbox there was no noticable extra wear so I'd happily believe it would have done many more miles if the gearbox hadn't passed away for another reason.
It does however seem it only applies to R380's, also from what people have said it's not a case of all undrilled gears had short splines and all drilled gears had long splines.