There are a couple of options now of syncing more than 1 camera during imaging runs.
APT - AstroPhotography Tool -
18.70 EURO http://www.ideiki.com/astro/
Multiple Camera Sync in Maxim DL
£50 (uses a Slave / Master setup) -
http://astro.neutral.org/software/mu...ync-maxim.html
Sync'ing to ensure dithering occurs when the other camera is not taking an exposure is key. Its a difficult pipeline to get working, but when you do its WideField / Narrow Field bliss.
stefan