Quote Originally Posted by Rich

Some long time sidemounters I know (who don't do it for show!) use an H-valve on one of their tanks with an extra pressurized reg attached, kinda eliminates the having to switch first stages deal.

Safe diving,

Rich
That's a good idea. Especially if you are doing a lot of the 'might as well be solo' kind of diving. Spare 1st stage. Redundancy.....duh. 8)