I have Cobra 3W and 7W and a Rocketbalz 5W. I have not hit the Ping G20 woods. I like both the Codra and the Rocketbalz although I can tell you I hit the Cobras more consistantly. My Cobras have senior shafts, the Rocketbalz has a regular shaft. I'm 62 and my swing speed is lower these days, I think the senior shafts help. The rocketbalz purchase was more an impulse buy one day, so I probably didn't get the correct shaft, I purchased it off the rack. I may be looking to sell it in the future given I hit my 7W almost as far as the Rocketbalz 5W.
Also, I would not believe the hype about 17 additional yards with the Rocketbalz fairway wood. That only applies to certain swing speeds according to Mark Crossfield on You Tube. If you haven't seen Mark Crossfield, I would go to You Tube and do a search for him. He gives instructions and also demos clubs. He did a comparison of the Rocketbalz and the Burner 3W, got the same distance with both clubs.