[Mithadan]

I've not gone back to read this entire thread so I may simply be repeating what some other member has said here. The relative strength of the Balrog's opponent may be entirely irrelevant to the question of whether the combatant can survive. There appears to be an unwritten rule in the Legendarium that "he who slays one of the people of the Ainur must also perish." Indeed there is no case known where one who defeats any of the few Maiar reported as slain manages to survive. Ecthelion and Balrog, both died. Glorfindel and Balrog, both died. Gandalf and Balrog (or Balrog and Gandalf), both dead. Wormtongue and Saruman, both dead. Elendil/Gil-Galad and Sauron, all dead.

My, isn't this just so pleasant?