Never driven SR with yam 75. We had a mariner 75 prior to 90 opti.
I ABSLOUTELY loved the SR with the opti. Its throttle response was awesome and it flew! Never found it stern heavy personally. Either before or after we blocked up the hole. It flew off waves well.
Only issue we had due to weight was reversing! Any waves and you got wet feet. Though I believe that's the same on all SRs as the transom is so low.
Personally I'd buy the set up again....unless given the choice of a Delta Dash with the higher sheer bow!