Maverick is dead on with his comments regarding the Saito 72 vs the OS 70 MKII.
Both the 70 Surpass and the 70 Surpass MKII put out the same power which is noticeably more power than the Saito 72. The 72 is only slightly lighter than the older 70 Surpass which is slightly lighter than the MKII version. Smaller mounting dimensions is where the 72 pays off. BTW the Saito 91 is only 1.2 ounces lighter than the 91 Surpass and does not have more power - this is an old wives tail at best.