Can't see why motorized tilt only would be worth it. Motorized auto training would be much better.
Your optimum tilt when facing South changes by approx. 8 degrees a month over a six month period due to the sun's declination from pos 23.5 to minus 23.5. You get 10 degrees forgiveness in amps results by not having the panel directly aimed. So you would only need to climb up there maybe once a month.
What is much more valuable on a daily basis is to train the panel towards the sun during the day while it is already tilted. In fact you can get away with three moves a day to SE, S, and SW and still do fairly close to all-day moving. Ideally, you tilt it higher earlier and later in the day as the sun goes up and down.
If your panel is on the roof and it is not convenient the way it is mounted to train it during the day, then just tilt it up manually at that month's optimum angle and leave it alone.
Manually:
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27734213/gotomsg/27734213/p/1.cfm#27734213