I only installed the front mount. Vibration is minimum. Installing the rear mount is a PITA and vibration will be extreme mainly because the mount is right against the firewall so all the vibration will come in the cabin. I thought about possible damage for just installing the front mount. Since the front mount is now stiffer than the rear mount, all the forces/stresses are being transfered to the stiffests mount (front). This also applies to structures ( I am a Civil Engneer). The rear mount will not wear faster. The front (stiffest) mount is talking most of the beating. The only thing I am worried about is something happening to the front member because of the extra stress. Only time will tell, but I am glad I replaced the front mount. The stock mount I could bend with my little finger. It is a joke!!
I don't plan on installing the rear mount bause the vibration would be unbearable for a daily driver.
BTW, stop the misinformation.