Large Scale Central

Air operated switches

Hi all,
At this time I am starting to plan for the 2006 garden railroad season. I’m wondering if anyone can tell me the PRO’S and CON’S on powering my future switches with air. The switches will be located outside and on the ground and the track is brass. Also wondering if I should start out with manual or electric switches. At this time I am using track power.
Thank you for any info that you can provide,
Ron