The weight of a small paper clip is about one gram.
I just moved from a 47 gram yo-yo to a 64 gram yo-yo, and not a whole lot changed. I did have to adjust how hard I threw by a little bit, especially on Around the World’s where the newer and heavier yo-yo (which also spins much faster than my old one - this contributes to the force the yo-yo has when it returns) would smack the crap out of my hand if I did a triple loop and then jerked it back the way I did with my smaller yo-yo.
But really… No. That’s a considerable change in weight. My new yo-yo is a butterfly as well, and the old one an imperial, so it’s not just that the weight changed. It’s that the weight distribution also changed.
A) The new yo-yo outweighed the old by 20 grams or so
B) The new yo-yo spins at least twice as fast as the old one, if not more.
C) The new yo-yo is a butterfly, and the old one is an imperial. The weight distribution has changed completely.
But none of this caused me to have any extreme change to any of my motions.
I strongly suspect that a lot of what people who take yo-yos seriously do is psychosomatic, meaning that for whatever reason it creates a psychological comfort, but doesn’t actually affect outcomes in and of itself.
A person might get more used to any given component of their yo-yo (the shape, weight, string, bearing, pads, etc) and subsequently might commit some very subtle nuances to muscle memory, but to actually be of a significant impact on a yo-yo?
Anything within a few grams is going to be completely undetectable to most people. Even if someone is used to 65 grams of a yo-yo, and it suddenly changes to 60 grams, it might, mildly, somehow, some way, make some minor difference in how fast or hard the smaller yo-yo returns, which might consequently require a small adaptation for someone’s traditional motions.
But in all honesty, that small of a difference is probably not going to affect anything. I suppose some of it matters if it changes the weight distribution considerably - for example if the weight of a yo-yo is balanced between axle and rim, and suddenly 4 grams of weight are removed from the axle area and this doubles the ratio of weight on the rim to the axle, this might make a difference in behavior for the yo-yo. If we then couple that with the inert weight of a yo-yo in motion (small differences in weight can be amplified while spinning or throwing), under the most extreme of circumstances this might become reliably detectable to a person who is well attuned to the behavior of yo-yos.
But that still doesn’t mean one weight is better or worse. It just means they’re used to one versus the other - even among those who are ultra-cognizant of such things.
But if a person was as used to the new weight as they had been the old weight, they’d be fine.
In the vast majority of cases, especially if yo-yos are shaped the same and otherwise equipped the same, I strongly suspect that the weight is entirely psychosomatic.
I could be wrong, but my guess is that even among exceptionally good yo-yo players, if we conducted a double-blind “weight test” on two identical looking yo-yos, even professional yo-yoers would guess the heavier one about 50% of the time - perfectly on par with a random sample, and comparable to what you’d get if both yo-yos actually were identical (including their weight).
It’s such a small difference that it would really only be noticeable to the very most perceptive yo-yo players, and even then only under an extreme set of circumstances.
That’s my take on it. Apologies for the long post.