Ok, I did some scientific testing. Here are my controls:
2x PS360+ boards
P1 in legacy mode
P2 in native mode
1 iL button wired up to 1K on both boards
Vega was chosen for character select since I’m most familar with the character
Attack used is s.LK (1K on the board) @ 3 frames start up, 2 frames active, 9 frames of recovery
P1 at point blank counter hits P2 100%, tested for 30 attempts
P1 at max hit distance trades 100%, test for 30 attempts
We can gather from this information that legacy SG driver is 1 frame faster than native PS4 in Street Fighter 5. This is calculated because P1 legacy always counters at point blank, meaning it beats the start up of P2 native before it becomes active. This is at bare minimum 4 frames, the first frame s.LK is active. At maximum distance, both trade because at frame 3 on P2 native is out of hit range, but frame 4 is active however in the range for frame 5 on P1 legacy to still hit. If P2 native was 2 frames behind, both attacks would whiff or P2 would win depending on how far the hurt box sticks out during recovery frames since P2 would still be active during those frames. From what I’ve seen of the hurt boxes during recovery, P2 should win if it was lagging behind 2 frames.
To be safe, I tested P1 on P2 side and the results were identical.
Basically, every TO now has to deal with the 1 frame lag headache and everyone wanting to use legacy mode. Thanks, Capcom.
Another note, if you’re playing the game using a converter, you’re going to be about 2 frames of lag behind a legacy controller. Brook converters have low lag, but it will still be there. I’ll try to test that situation out if I can. if P2 beats P1 every time, then that would mean P2 is lagging 2 frames behind. I’ll see if I can get some of those going, too.
Update 05/20/16: Adding a video. This time I tested the Brook UFB for repeatable data. This time there is no converter test because I don’t have a USB PS3 to PS4 converter. If I can borrow one I will test again.