The DeDion held the road better, until it didn't, and then let loose in a manor that was just about uncorrectable. I'm sure it has a lot to do with the lack of camber change. This seemed to happen when you drove it on the edge, which most don't anyway, so for most it is/was a non-issue. It is easier to adjust and you can change spring rates, compression, rebound, etc... with sock and spring changes, so that was an advantage and it really drove nicely in most instances.
Something else I didn't like about the DeDion (and this was just my own observation with little engineering to back it up): the Watts link is what holds it from having lateral movement, however the Watts link sits in the car at an angle, let's call it 30 degrees, connected to the chassis at the top and the suspension at the bottom. As that suspension moves up and down the Watts link is also doing the same, on the suspension side, but it is changing angle as it swings through its arc. If you can picture this Watts arc and compare it to the suspension moving straight up and down, the Watts arc will actually pull the suspension slightly left and right, effectively unsettling the rear end, so you have a live axle that has a little bit of built in oversteer... On small bumps, small compressions and rebounds, and etc that change is small but hard bumps, suspension unsettling or hard cornering it increases the lateral motion.