by Whymme
I'd like to play the regular game with expansion a few times before trying out this variant. That way I can estimate the impact.Apart from that, it sounds like a good idea. I think that being able to see when a new tech comes into play is fun.
As a compromise between those who want the tech open and those who want the tech hidden, what about putting techs down hidden (by blackening one side of the tile, if need be) and turning each one up on the turn before it would come into play? So at the start of turn 6 you reveal what rare tech becomes available in round 7.