I'm adamant about it on principle. People have a tendency to oversimplify things, and this isn't a simple question. Personally, the difference doesn't feel like an ogre bicep compared to a midget dick to me.
To explain why this isn't a simple question, remember that we aren't talking about simple force applications here. For starters, we need to consider how quickly force can be applied in each direction. Second, we need to consider that the key's spring is pushing upwards at all times; it necessitates a higher force on the press, but it can literally lift your finger back into neutral position on the release. Third we need to consider that we aren't just using fingers here, every player's motion is hybridized to some extent. Finally, we need to consider that all of this is time-sensitive. As long as the key's spring can lift your finger past the actuation point before you need to actuate it again the spring is providing force in excess of what is necessary, and that excess eats into your stamina. The question of whether the extra return force of blacks is valuable depends entirely on how long it takes the key to lift your finger past the actuation point; until you reach such a speed where the extra 15g becomes necessary reds will be superior.
At least, until you consider that the distance of the keypress is variable, and that the force applied by the spring is not linear, and that each player's movement is not consistent or uniform, etc.
This is a tough problem. In the end it probably doesn't matter, but if we're gonna pretend that it does let's at least try not to screw around with it.