I, too, am a bit uneasy with the description of how the save slots work. The "saved party" option seems entirely too rigid, at least as it's been described. What if one member can't make it one day? Then, nobody can progress. Or, a worse case, what if you've progressed deep into the dungeon, and one member suddenly drops from the group or quits the game or whatever. That save point is now useless since you can't enter with your saved group. The remaining members all now must start again from square one?

It seems like it would be much simpler if you could go in with any party, at any time, and progression would default to the furthest-behind member of the party. That way, if you have a group of four friends progressing together, and one friend can't make it to a session, the other three can continue on while the fourth makes up the difference on their own (or with another party) until they are caught up again. Then all four can continue on. If a person permanently drops from the group, it's easy to bring in a new member at a similar level of progression.

Perhaps the party save option isn't as bleak as I'm painting it, but right now it looks kinda bad...