Thanks Jacqueline and Doug,
Jacqueline, the “smooth” is only applied to the position keyframe, not the scale. As far as I can tell position and opacity are the only two types of keyframes that can be eased in Final Cut. As a keyframe junkie who started as an After Effects animator this annoys me. The best way I have found with stock FCPX to create the move I was describing is to do the KenBurns crop with an ease on the still, make it a compound clip, then put a hold at the end. It would be nice if you could keyframe the Ken Burns crop, but that doesn’t seem to be possible.
Doug, the shortcut plugin you posted looks promising. I’m also looking into using motion to create some custom plugins to facilitate my workflow.
I still have some love/hate with FCPX, but ultimately I think its playback performance, painless background rendering, and stability (not to mention price) make it worth the switch.