I'd be willing to bet that, based on the "ride around the block" test, I'd have a much higher accuracy guessing chromo vs hi-ten frames than you'd have guessing shaved bead seat vs unshaved.
And no, a few grams of imbalance in a rim will not produce the same effect as a hop.
I'd say we'd have the same probability, it's 50/50 in each case ? Hi ten or chromolly, shaved or unshaven ? We both might get lucky and guess right too ? With hi ten vs chromolly, many threads here @ BF show pics of a vintage bike, many have to go research it because they aren't quite sure. Then again, shaved or unshaven, every weld on a rim is shaved, has to be, just depends upon how meticulous it was done ? But you know what, I have complete faith and confidence that you can tell the difference between hi ten & chromoly.