I was very confused about identical independent copies before. Right now the view given here is the best one I have thought of---more independent copies are more significant, just like copies running on more easily specified substrates. In this view copy immortality has no value--there is no difference between 2 copies with probability 1/2 and 1 copy with probability 1.

I have no idea how to choose a notion of complexity, either amongst UTMs or over some broader class of descriptions. I hope that at some point I will encounter a good argument for one choice or another, but I don't yet know of any and its not clear why there would be a good argument.