It's a sound advice!
Please note that by sliding the saddle backwards you seem to be in the search for more Reach. That would put your body in a more aggressive position, and part of your body weight will be shifted off the saddle more onto the bars, making the saddle more comfortable. You mentioned
Specialized road bikes: Was it not that you were really leaning forward on the bars there? That explains why you felt more comfortable on road bikes.
For me, the Bridge Sport (the same saddle you have in your Vado) is the most comfortable of all of my bike seats but I did a lot to increase the Reach on my both Turbo e-bikes to ride in a sporty position that shifts my body weight off the saddle! (each of my two Spec e-bikes had too short Reach as for me).