There are two save points within Memoria, one at the beginning and halfway point (about). There's also a third towards the end, but that's not technically in Memoria. Hades can throw you for a loop if you're not prepared, but he can be overcome with the right setup.

And really, if you skip Hades, there's no way it should take 4+ hours to get through. There's only four bosses, some of which aren't too great, and you can flee from battles like they'll give you leprosy. Hour or two tops, depending on your levels. [NOTE: You can always come back and fight Hades, so don't think it's an imperative to do it while you're there. Backtracking to that spot isn't as time-consuming as you'd think.]