Hey Whizz.
I have the medium cruiser size. Check out the new model which has a cut-out at the front to cater for the man bits. I think that one will be more suitable than the medium cruiser. I find the medium cruiser one a tad long as it either sits up on the tank a little or if you move it towards the rear of the seat, tends to push your bum forward in the saddle because of the shape of the back of the seat.
I still find it's a big improvement over the OEM seat.