With a good polar alignment I used to get consistent 60 second unguided exposures with my old EQ5 + 5DmkII + ED80 so I should think you could get at least this with your scope/camera on an EQ6. 60 seconds was enough for reasonable images of the brighter objects with my 5DmkII.
I looked into the Synguider a couple of years ago and it sounded just ok but I didn't move to autoguiding until I got a CCD and by that stage I had to have my laptop with me anyway.
Astronomy Shed did a review of it here:
http://www.youtube.com/watch?v=yIkLUOipCSc