Have played this game since day one, and well past the Halo 3 beta.. lol

One of the highlight features of this game is Key to the City, a mode where player defined level upgrades, god mode, and full city wide access to supply points is available in the first minute of play.

I'm proposing adding a category for "KttC All Bosses", and have a run viable as concept here already.

I initially started running the NG category, and found the nature of resetting and creating a new profile each attempt to be annoying.. motive to continue running was low. Keys to the city does not save progress, and can be reset in a simple manner. It offers routing with supply points, and a whole arsenal selection.

I think it would be a healthy category for the game! Possibly some Co-op section for NG, NG+, and KttC in the future for RTA?

I have a friend who has the game on order, and we plan on having a Co-op concept run in the next weeks after he's learned the game.

Keys to the City is free on Xbox live as far as I am aware.

Slow-as-molasses reply here.
(TL;DR - I don't think KttC is necessary, NG+ is friendly enough, and just go into NG by not loading any saves/using an Xbox 360 profile for quick resets and don't care about achievement exp, it's not worth the headache)

I couldn't comment on any co-op categories (maybe there's some interesting split duties that works out), but I'm not too sure about KttC personally. While it appears to change a few things here and there, such as jumping up Wang's tower and (maybe, haven't tested it) climbing Cowell's tower from the south (so re-warping to Stripey's Cafe), I'm not sure there's enough to differentiate it from NG+, and NG+ is overall a fairly accessible category - the only thing that might not be straightforward is knowing that the supply point warps have position memory between save files, so those need to be chosen before resetting. Although that reorder for Fang-Yin, Timbol, and Rzeznik is something I hadn't considered. That's actually a time-save, thanks.

On your gripes with NG: I have the same issue. That said, just don't bother with setting up a new profile and ignore the achievements, they're nearly all just for agility anyway and only a couple matter (so it's just a couple of extra orbs, and on XB1 I think the faster initial loading time counteracts the achievements, maybe 360 is 1-2secs faster?). Don't get me wrong, it's still far more brutal than NG+, but you can make it work, and on XB1 you can tell the console to not load any saves so you can start fresh without deleting NG+ data (I forget the exact details on how to do this, though, it's been a while).