Swept wings don't do much, it seems.

[Wjolcz]

Once the BG robotic parts came out I started experimenting. I built a plane with 2xJuno and moving wings a'la simplified F-14. Got to maximum speed, bent the wings back and watched the speed. Nothing happened.

[Cavscout74]

The KSP aerodynamic model isn't the greatest so that isn't very surprising.  There is a mod that creates a more realistic aerodynamic model called FAR but I don't many details about it, so I can't say if it would make a difference there either.