I’m afraid it’s more than just weight. Throw, rebound, repetition, all of those vary drastically between piano actions and synth actions. My K2500 is about the only thing I ever played that tried to be a halfway point between synth and piano, but it falls short of being ‘great’ at both. It is what it is… heavier than a synth, lighter than a piano. I guess if I was doing 50/50 it would be the best compromise, but if I’m honest, I'm probably more 70/30 non weighted sounds over piano.

And, of course, the downside is weight. My BK9’s 76 is comparable in feel to say a PA4x, but the better feeling G70 also weighed 25lbs more than the 20lbs BK9, and having removed both actions at one time or another, I can assure you that probably at LEAST 5 of those extra pounds was the action! Then the heavier support weight needs to add more. I'm fairly sure adding a G70 action to a BK9 would have bumped the overall weight 10lbs or so…

For me at my age (70 creeping ever closer!) my main concern is to stress my hands and fingers as little as possible, so while I lose some touch and control playing piano and Rhodes on a synth action, hopefully I’m gaining a few more years of playing without pain…