Summoned dremoras generally didn't bother my character - but he had 'banish' on Conjured weapons. One arrow could not kill my dovakiin - you seem to mix reality world with fantasy at leisure.
But I'm done with this conversation - I personally think the dovakiin would prove a powerful ally, other dismiss him as a one-shot kill. I guess ultimately it's how we individually perceive the fantasy world of nirn.
This is more of a personal character question, everyone's profile is different, this is just your personal character, and as for getting involved, the Dragonborn would be useful, but the dragons could be taken down, and the Dragonborn could be ambushed, poisoned, or assassinated.