People really need to do a reality check on servo based cam pan/tilt systems. Nobody can expect to get a $15 hobby servo pan/tilt to compare to a $1.5k servo pan/tilt, or a $150k professional cam conrol system. As to hobby servo based pan/tilt systems, the quality of operation depends a lot on the quality of design and control used in the construction.
http://www.servocity.com/html/pt-2100_pan__tilt_system.html
http://www.servocity.com/html/pan_tilt_roll___accessories.html