480 pound Yamaha 150 here. No complaints.
My first 189 had a 473lb (I think) Merc 175. Seemed fine to me. I do understand overloading the stern. I've had bass boats. I am just ordering a new boat. After attempting to take into account of everything (including $) I just agreed with Frank to put a 150 Pro XS on it - 455lbs. I guess we'll see.