Someone tested it, the Cobra is actually more maneuverable than a Viper in every axis except yaw:
https://www.youtube.com/watch?v=DnAVUIo2420
The issue is that it is
significantly heavier than a Viper, so it takes longer to actually change direction. The C1 hardpoints are mounted at the back of the wings on the bottom of the ship, so hitting anything above the midline of the Cobra is just about impossible. It's also a far bigger target for someone using fixed weapons and its shields are weaker than a Viper's.
That said, it's faster, has a significantly larger power plant, so you're less likely to run into power issues (you'll still have trouble if you try to run more than one Shield Cell Bank), it can actually carry cargo, it's more heavily armored (with military grade bulkheads you'll be able to sustain a good amount of punishment if your shields drop) and has a much larger jump range. My A-Graded cobra, fully loaded, can jump almost 18ly, empty I can jump 20. If downgraded a few components to D (sensors and Life Support come to mind) I could jump even farther, have a faster boost rate and change direction slightly better.
I like my Cobra ;-) It means I don't have to keep a ship in storage to do what I want to do on any given day.