Well, the plants will tell you if your bubble rate or if your flow/distribution is enough. It's impossible for anyone else to tell what is sufficient simply from a bubble rate. Everyones bubbles are a different size so we cannot use this as a reliable or as an objective parameter.
In any case, what Dave and I are saying is that any wpg upgrades should be ignored and first you need to get a grasp of the technique of CO2 injection. By far, the overwhelming majority of problems with plants are directly attributable to poor application of CO2. After you understand the effects, importance and application of CO2 you can then move forward with lighting upgrades. The two are directly related. More light means that you need better CO2 so it's a more effective strategy to perfect your CO2 and flow before attempting anything else.
Cheers,