that's very interesting...
why do you need a single keyframe and have the object NOT do anything else in the play range?
In my copy of M5 .2, if I set a position keyframe, the only keys automatically created are positions. For scaling, I had to manually add a scaling key to start recording scales. Automatic keyframing does not fire keys for position, scale, rotation, etc., unless I start one.
However, they will automatically keep recording while playing the timeline (just as if Record is enabled). According to the manual:
Choose Mark > Recording Options.
Select “Don’t Record keyframes during playback.”
And motion will not record changes while the project is playing.
Also, it is still possible to move the entire keyframe/motion path. Command-option click anywhere on the path and you can drag it around. You can drag around only segments of the path by simply clicking on the path between two keyframes and reposition it. Etc... (it's all in the manual.)
If I switch over and use the "Record Method", then the "Initial Keyframe" method is not used.
And, if you just need to start over without keyframes, there's the Transform reset button which clears all keyframes in a click.
It all seems very cool to me.