Ideally there would be a category for every 5 levels, or at least 10 levels. If you're 70-80, you're really not competing with your peers, when there are people 90-100 in the same category. 30 level gap is ludicrous, it really is. I can think of another game right now, that has competitive "battlegrounds", the tiers are broken up into level ranges no bigger than 5, and then they scale the lower levels stats up to make it more balanced. No need to scale the damage up, but at least make the categories more competitive.
If you're level 70-80, are you really going to pick up an LR-60 (L), or something similar that's in good stock, and expect to win this thing? You'd just be doing it for fun. I want to participate in the event, and I want to be competitive in it. To hell with spending 100k ped or whatever it is to chip up to 90 from 76 for that though. What kind of competition is it when I know I'm going to be squashed before I even try? MA/PC needs to put themselves in the shoes of a lvl 70, with a budget of 10k peds, which is probably more than the average lvl 70 has to spend for mayhem, and try these events for themselves. Then realize how futile these mayhem events are for a good deal of us. At least for feffox/halloween/solo merry mayhem. The team mayhem is actually quite a nice event to get everyone involved, but is more of a hassle than the solo version.