After deciding to try Heroic Ultraxion for the first time last week (taking a break from Hagara attempts), we decided that he looked very doable. With the help of an additional 5% nerf this week, we downed Ultraxion quite easily.
Now if we can have a single week in which we have 10 raiders available both nights, maybe we can make some progress elsewhere... Incidentally, we're looking for a decent, reliable mage, warlock, shadow priest, rogue, paladin, or death knight to fill an otherwise empty DPS slot.