Yes they do have nice stuff, but a double dropchecker? This is an illusion of the highest order. Let's do a mini-reality check: Raise your hand if your current drop checker is green and you still have CO2 related algae. Well, if you raised your hand that means the problem in the tank is more profound, such as poor flow or poor distribution, or too much light or any combination of these.
Blindly trying to modulate your bubble rate to match some arbitrary reference color is akin to hypnosis. Who cares what the reference color is? Look at your plants. They tell you what the status of your CO2 is. The lime green color is merely a point of reference that we ourselves advocate, but with the proviso that it should be used only as a guide. Your measurement color could be more bluish than the reference color and you could still be fine, or, it could match perfectly and you maybe in real trouble due to the factors listed above.
I use the diffuser you show and it does affect the flow rate but not as badly as some diffusers so it is a good one and is attractive as well. I just wish Cal Aqua had spent their R&D money in developing a diffuser with larger capacity, and larger diameter inlet/outlet spuds knowing that there is a trend towards larger planted tanks, instead of conjuring up this prestidigitation.