Opinions? As long as you dont crush driver, its fine.. I saw that mesh even replaced, whole cans made out of wood etc. Only important thing is drivers.
If you fixed it and it works, its ok..
Aehm.. there are difference between line-up.
555 have with this "tape mod" quite nice and clear sound (yes, less bass, but they are bit over-bassed from start). 595 are pretty much same, but have bit crispier sound. Its not much, but you can hear that..
HD 600 .. no clue, but should be similar to HD 650, just with less over-bass. Sells are 10x HD 600 on 1x HD 650 on 100x AKG 701.
Which can give you idea..
HD 650 are.. well, hard to describe. Certainly less clear than HD 595 or 555.. which I find bit tragic, considered price.. it can be due cables being not exactly top quality, there are rumours from ppl that changed them for better, that it helps a lot.. but better cable can help quite a lot even on HD 555/595. Plus they are plastic, which seems pretty awful for this price range.
They are sound upgrade from certain point of view, cause you hear much more of the music, but in same time it looses clarity and crispiness of lower models. And its heavy handed over-bassed. Which I think its almost unaceptable for "reference headphones" (it shouldnt alter sound at all).
HD 800 no clue, its considered as top of real reference headphones, which probably means they sound like they should..
So as you see, there is difference in line-up.
