I didn’t mind level drain in and of itself. I mean, I FEARED it, but I wasn’t against its existence in the game. The main annoyance for me was dealing with it for multiclassed characters. And the vast majority of my D&D PCs are multiclassed. Not only was the math tedious in those cases, recalculating everything was
S-L-O-W.
I also felt the “draining levels” mechanic was a poor match the lore of “life draining”. So I had started testing using the 3.5Ed’s fatigue mechanics instead of level draining. It was
much more streamlined, meaning the penalties were easily and quickly calculated. It caused problems for any PC, so the fear factor was intact.
The one flaw: it was TOO good. With level draining, a PC might be able to survive a handful of drains, but the same number of successful fatiguing blows would drop any PC, regardless of level. And the level draining spells & powers were likewise as problematic. Before I could rectify that issue- probably by making successful drains rarer- 4Ed was announced.