I've recently tried regrilling the 560's. Differences are there, but very minimal. To my ears, the 560 has a bit of glare in the upper mids similar to the HE-6, but while the 6 is a bit more broadband I find the 560 is more focused. Switching from the focuspads to the focuspads-A makes a bigger difference, though I feel it more just moves the glare to a less objectionable spot. Regrilling the 560 reduces some of that glare by a smidge.
Right now, I feel I have achieved a good balance with the regrilling and a couple strips of felt in front of the focuspads-A.