Well, I gave it a go and ballasted a section of my track......the large curve at the end of my freight yard. I found it to be messy to apply, even with the 3 rail hopper/spreader, and the brass rails became dirty/dusty in the profile of the "bullhead", down to the top of the ties. In the area where I haven't installed the "green" base mat, the ballast falls into the small holes of the soundproof underlay, and looks a bit messy along the edges of the track.
I have attached a couple of photos of the ballasted sections so you can see for yourselves how it looks. I am still in two minds, but I am leaning more toward the "toy train" position, more so than the "model railroad" effect. What I do like is the sound deadening non-slip underlay I installed over the entire benchtop. It works a treat and has dramatically reduced the running noise of my trains. Loco's just glide around almost in silence, and even my wife has commented on the lack of background noise coming from the garage now. I can even now hear the radio now while running trains.
Thanks for everyone's advice and input, and please let me know what you think of my ballast results before the hammer falls.
Peter on the fabulous Gold Coast in sunny Queensland, Australia.