Tried this out on Emperor (I still can't make the jump to Immortal). Save for a 40-turn war with two neighbors (turns 70-110, not a military unit from both were seen), I managed my best SV since I started playing (okay, not quite, but all the research was basically done by me). Turn 289, which could have been faster by around 10 turns, had I just gotten a scientist with PT. No Research Agreements were signed. Settled 5 scientists total (3 on Capital, one each for my Observatory cities).
Looks like in this game, if you want to set record victory times, you really have to play Diety. IMHO, RA's aren't worth signing Emperor below, since rarely do your neighbors have the funds, and when they do manage to scrounge up, they're way too far behind for it to matter even if you have PT and Rationalism finished. Also made my guilds on my projected three science cities (cap and observatory sites) to really boost up my science. Needless to say that internal trade routes (Sadly, no boats) allowed me to get scientists while keeping respectable growth. I think I had a maximum of just three international trade routes all game.
I have to say tough, that getting Collective Rule without sacrificing Tradition and Consulates is hellapowerful.