"Nice.  However, the Morphbrush in my Poser is evil.  You must have gotten the "good" one.  Mine stares at me, daring me to take it out of its cage and murder figures to death with it.  Pure evil man, pure evil..."

The #1 secret is playing with it's magnitude.
The default strenght (magnitude) of 0.2000 is way too high and only good for smoothing.
For everything else, sculpting and morphing, you need to use A LOT lower magnitude, like 0.0100 to 0,0050

You also need to learn when to switch between "surface" and "screen" to get the morphbrush to do what you want.

There IS a learning curve, but It's definitely not as steep as learning other brush-sculpting tools like Z-Brush.
IMO, learning to use the MorphBrush tool to permanently fix a joint isn't harder than learning to use the paintbrush in Photoshop to do postwork.
And unlike postwork, once you "fixed" a joint, you never have to do it again.