Not a Bennington, but I have a friend that has a 25' Avalon Catalina Platinum with the triple 27" Waveglider package sporting the Zuke 350 donning the counter-rotating 15.5x19.5 prop setup.
He can top out at 48 MPH with 3 adults, 2 kids, and a full tank. His goal is to hopefully get it up around 55 MPH with just him and 1/4 to 1/2 tank, but I don't think he's tried that particular speed run, yet.
He's got no complaints, although he just took delivery back in July, so it's barely out of the break-in period.