I never said that I am not a good photographer and so I didn't need the best quality of light. What I meant was that there are many other important things that will have a larger impact on your image quality than whether you use a top of the line strobe or a premium strobe. Because we are not talking about some little YS-01 or sealife strobe here, the Z330 is a very good product.
The most important thing is knowing how to use your gear, of course it's better to have a higher quality of light, but how big of a difference is there really when using these two strobes underwater, compared to the cost?
I am still using my old 16 MP Oly OM-D E-M1 and a couple of YS-D1s and I regularly get much better results than people with much better/fancier camera setups. Knowing your gear and using it the best you can will take you much further than just buying the latest greatest stuff. That will help too, but you don't need the latest and greatest to win awards.
Sometimes I feel people get too caught up in comparing every minute spec and every little nuance of image quality when that isn't what matters the most.