I think I've suggested the best way to do that.

I have an SL7 (7kg) and a Mk1 Diverge (9.2kg), both geared almost identically (Diverge has an 11-34 cassette, the SL7 an 11-30, both driven by a 52/36 chainset), and the SL7 definitely "feels" easier to climb. But, Strava says the difference is strictly based on how many beers I've had the night before. Both have carbon hoops on, though the wheelset on the Diverge are a touch heavier with 32mm slick tires on, but the SL7 is wearing 30mm right now. My point is that the minimal differences in weight we are talking about are really not going to make it "easier" to climb. Gearing will do more for you in that respect. Even then, there are limits, lower gears might be easier to turn but could end up requiring more work (effort over time), and then you have to ask yourself "Was the climb actually easier?"

Bottom line: I don't think 650b is going to get you "easier" climbing.