I have done both the climbs in question and i did find the 21 on the arete much more harder
than painless and would agree to the grading. I felt that it had more committing clips and
harder moves. Painless was a bit daunting at first but on the second time i climbed it i felt
it was easier than a 20...more an 18.
There is also that two carrot 17 on the bolder below painless i think its called mercy and i
could not even get off the ground.