I would say that having one smart non-Eliezer person working on FAI together with you would be preferable to having two or maybe even three copies of EY. The copies are likely to have similar thought patterns, have similar biases and make similar mistakes.

It depends on the topic. If the problem can be solved by lots of hard work and this hard work can be done in parallel, then copies are a good idea. If the problem requires inspiration, perhaps in many incremental steps, then more diverse minds would be preferable.

I think what I am trying to say is that marginal returns diminish faster for copies compared to other people.