Richard,
I would usually do this in 8bit uncompressed. In FCP I would use a very cool generator called PanZoomPro from lyric.com. I would say this method is about 4-5 times faster than the motion tab and there are NO KEYFRAMES.
But, these days when I have a photos-only project more and more I’m using a different app called Fotomagico. Just yesterday I animated 80 photos of my daughter growing up for her upcoming wedding video, came to 6.5 minutes and did it all with buttery smooth Ken Burns-type moves in less than an hour. It lets you output to any format you want. Yes, you can add audio if you want.
These two solutions are about as fast as each other, but I’d give Fotomagico the edge, especially since it renders faster.
Good luck!
Have a wonderful day.