Well I did play legitly with a group of 4 others (in assist mode). We lagged quite a bit in Ortel's castle and nearly all died (used revive feathers).
However, it took me 20 minutes to clear the first floor (even with OHK + movement speed change) in solo mode..
I also noticed there was no records on the board. Its not really a spammable dungeon either.
I skipped to the second map but I still had to clear out quite a bit of enemies