Following Neil's comment that I focus too much on the Void, I decided to actually try it. I'd killed Morgoth in pre-2.2.x versions, so I was curious about the 'ultimate' ending. Of course I'd read about Lord Dimwit's multiple successes there, so I figured it couldn't be impossible...well, it's darn close.
vanquished Melkor today after wading through hordes of demons, which plagued him far more than Spirits. It's rather like playing a lost soul. You have to keep track of the stairs while looking for the next set, always ready to beat a hasty retreat. High stealth definitely helped him avoid waking up demons, which effectively caused dozens of potentially-summoned monsters to not exist.
Paradoxically, the Nether Realm seemed easier than the Void, even though everything was level 150. This is probably because most of the monsters were trapped in nice little vaults which block LOS.
Tantar had a little surprise when he took the stairs up from the top of the Nether Realm back to Lothlorien, and another when he took the stairs up from the bottom of the Void to the Halls of Mandos.
Anyway, it was a fun jaunt, and as always, thanks to Darkgod for his constant innovation.