Lighter is always better, of course.
I don't know much about the SUV, but I've owned a Vybe for just over a year or so. There's a good chance that the Vybe will handle better on account of it's slightly more "aggressive" geometry (look at how both the seatpost and the handlepost are more "forward" along the wheelbase.) I've only ever ridden one around the shop floor for a couple of minutes or so, and I felt that the seating position was just to laid back for my preference.
With that being said, the SUV might ride more nicely, given that it's a steel frame.
Now, keep in mind that both of these bikes are price-leader, entry-level bikes, so you ought not to expect much in terms of initial quality. If you're forking out for an IGH conversion, you might as well lay down some more money for a better-quality bike than these two. If you're sticking with Dahon, any Speed is a very good chromoly frame, while a Mu frame will give you the added option of a belt drive, if you're so inclined (which isn't possible with the Speed because it has actual chainstays.) I can tell you with certainty that either the Mu or the Speed will handle and corner far better than the Vybe.