The leaderboard suggests that casual and normal are basically the same except Normal skips some cutscenes, but I don't think it's true. I tried a speedrun on Normal and noticed that I often had less than full health, and I consistently died during the final boss battle, about half-way through it.

It wasn't bad up to that point though, so perhaps it's worth starting in Normal and switching to Casual just for the final boss battle, which you can do through the menu.

Switching in the menu is extremely slow and not needed at all. With a small amount of practice, you can go without dying.

Of the ~100 runs I did last week I lost like 5 to deaths that were just not paying attention and ignoring packs. There are already too many categories, we don't really need to add any more.

Sure, I didn't mean there should be more categories... just that there are more differences than just whether the maps show up.

The normal difficulty is definitely recommended for 100% runs as you are going to collect a lot of health expansions and armour upgrades.

And going past even more map stations you'd lose even more time that you can't do anything about.