Yeah, .5 or so is my limit on most morphs.  Some lower, some higher.  I very rarely get as high as 1.0.

Sometimes I will also set up two separate expressions on different frames of the 'animation', keyframe somewhere in the middle and then spawn a morph target out of that, and then dial up that morph part way in initial frame before or after restoring.

That's a pretty neat idea.  I like your system in general, it's better than my idea :).