In addition to scrapping the whole concept of permanent max durability reduction, I guess I'd like any repair system to ensure:
1) There's no unrealistic equipment durability/quality "threshold" such that with a particular piece of equipment at a certain ability level, under the threshold you can do nothing, but above the threshold you can do anything.
I don't really see the current setup (where, with a Repair skill of 1, you can fix an item at 40/50 durability, but not 30/50 durability (without a Repair skill of 2)) as being unrealistic. I would expect a novice to sometimes run into something he can't fix.
"That's too badly damaged and beyond my skill. I can't fix that; I'd probably do more harm than good. We need a professional.".
Or, are you talking about something else?