You've made some very excellent points here. Perhaps a good explanation and reminder as to the similarities was what I needed.
Thanks The only reason I remember all of that stuff about the Legion is because I'm currently doing a Legion play-through. I didn't really notice the similarities either until this last play-through, and now that I'm seeing how well Caesar's application of history to the present is working, I have gained a lot of respect for the Legion as a faction. Respect for both the developers for creating the faction (I used to think the Legion was kind of stupid writing wise) and respect for the Legion itself as being far better than the NCR in most every way.
I didn't actually make the connection between the pre-Marian Republican Legion formation and how Caesar deploy's his forces. Is there indeed indication that he uses the hastati/principes/triarii deployment? Obviously in practice one doesn't see it because you can have Veterans attacking before recruits and such, but this is simply a result of game mechanics. So my question is of course based more in lore.
Oddly enough, Chief Hanlon is the only character that explains this (as far as I know at least) as I've never heard any member of the Legion say anything about it. Somewhere in his long-winded dialogue, he talks about how the Legion sends a wave of recruits first, then the primes, then the veterans. I think he says it if you ask him about the First Battle of Hoover Dam, but I'm not sure.