hmmmm how can i put this?
it really depends on your other accesories or how you feel during pk/exp. If ya feel that a lotta ppl hit u very hard, then i would go for the ROMS since ya'll get 40 more AC than imirs. But if u feel that the damage you are taking isnt high at all, and that you want to focus more on attacking, then surely go for imirs. You sacrifice 40 AC for AP.
if you are just exping right now, and you dont really care much about win/loose @ bdw, then maybe get imir rings, and maybe get a pair of +12 or 14 magic power rings (i think these would do more than imirs @ exping.... correct me if im wrong) they arent expensive... The 40 AC during exping wont make such a huge difference, and doesnt matter if u do EW, since 95% of the time you get hit its from their AOE or range attack.
However, just looking @ BDW, i'd say roms > imirs. Since in BDW you'll have rogues/warriors/bp's doing damage for you, i wouldnt care much about that lil extra damage, HOwever, the 40 AC can be a determining factor of a win or loose situation. With 40 more AC you can stay alive longer, to TP your party to help, or tp your party out of a dangerous situation.
To sum it all up, its basically a comparision between:
*do you want more AC or Damage? (since magic power doesnt work for monsters)*
Damage = imirs. AC = ROM's