I was also wondering about the breakdown if the ring if cut but time will tell. I bet mine will be way messier when done since I more the likely will do it by eye with a razor.
I also wonder if the notches should line up with the ones on the pvhes stem when done and if so you will have to put the stem in the correct way when reinstalling. I wonder with the pvhes if there will be to much airflow like the turbo. All this wonder and no answers yet.
I don't think there's a reason to worry about it degrading, I intentionally made one with very crude notches and have used it a fair bit without any issues I can detect. I did my first one free hand, it can be done OK but gripping it makes it easier to control. Maybe an old school 'roach clip'?
Lining up is not important I think, which is why I put four notches in with 3 on the PVHES, at best only one can line up......
I didn't find the PVHES and notched ring to be too open, but what do I know really? I agree, the notches make the stock stems behave like the PVHES does WRT draw....but without falling out (if that's a feature you're looking to maintain?).