I still don't get it :) ...

I see what you mean about collecting vectors between the current scan and all previous scans within a certain range. That makes sense and should get you more data. I do something different that gives me more gun data in Melee - I also fire waves from the position of all other bots alive on the field. The effect might be similar. This seems separate from whether you scale them by time when you collect and project them.

I was wrong about how I do the tick by tick projection stuff, but regardless, you want to account for the fact that the projected movement might change the bullet time you're using to project. I.e., you don't want to project the displacement vector 35 ticks if they'll end up 30 bullet ticks away from you at the projected location. I do it the same way many do for Linear or Circular Targeting: take their current distance / bullet speed and project the vector that much; get the bullet time for the new location and re-project; do this until the bullet time doesn't change, or I'm alternating between two bullet times.

Dunno when you last looked at Diamond, but the code has gotten a huge overhaul since the 1.6.x versions. I think it's a lot better now. But it might still be "sophisticated". =)