I weight about 74kg.
Board was a 122 x 36 (pretty small really)
Conditions were about 12-15kts cross onshore in small surf
Certainly the kite felt more robust than the sonic which can feel a little light sometimes. I haven't had any issues with the construction of my sonics though so I can't be too critical. I'd emphasize that the construction of the batwing really looks solid. I like it.
The batwing feels a little more c-kite like than the sonic. It pulls you off the water differently in jumps and I certainly appreciated the extra height it gave. I'm not sure how I felt about the insensitivity to bar position. At first I didn't like it. I couldn't tell where to put the bar. After a while I realised that the kite didn't really care and it didn't matter to performance whereas I find on the sonic this is very important. You can still over sheet this kite (like all kites) but it seems to come on softer. Which style is better - I don't know. I suspect that the batwing would probably be better when unhooked as there would be no need to greatly adjust the chicken loop. I also suspect that the sonic with its sensitive sheeting may run a little closer to the peak of all out efficiency. Different properties for different types of riders I supose.
It would be interesting to see how the 9m and the 15.5m fly. I think the biggest gains in kite performance (across all manufacturers) need to be made in the larger sizes which have generally felt a little slow compared
their smaller models.
For me its a moot point - I don't own the batwing and my kiting budget is expended for the season...