Mike,
This is beginning to sound like a broken record, but "like Bird says" is sound advice. The first couple of times I used the rear mower was a bit of a challenge, but once I got used to it, I realized that it offers some advantages that would be impossible with a MMM.
One thing that Bird did not mention, that I discovered the second time I was using the rear mower, is that it allows me to "back up" to a steep drop off (parts of our land slopes off at 45 degrees, and even a BX cannot handle that). I back up to the edge, and keep it "cantilevered" over the edge, then slowly lower it to the angle of the land, then I slowly go forward, while simultaneously easing the top link forward.
This allows me to mow the top edge, and below for about 4 or 5 feet. Before this, the only way to mow that was with a weed whacker. The rear mower takes a much bigger bite, and it takes a whole lot less muscle power.
The GlueGuy