Found out the hard way, when the instance owner leaves party directly after getting the bouncy-chests; the remaining party members get the boot so fast that its near impossible to get the loot-chest.
allow squads to join (10 or 50, but only 5players can join)
convert instance to Dungeon/Fractal type => but enable mounts? (maybe allow mounts in home instance with this fix)
or all of the above?