I dont see how ones better than the other. They are similar for sure. Considering this, I would say it boils down to tune up. If you didnt see any return over a old carb setup....not trying to be smart... simply put, your doing it wrong.
What size nozzle's, and bypass pill? How are you setting the idle circuit, and are you using EGT's as a tuning aid?
Although not necessary these can be properly tuned without a EGT setup.
You can use a leak down gauge for initial setup, I would say this would be critical, and somewhat difficult (its not easy with one) seeing there is two toilets. And Idle/butterfly setting along with barrel valve setting would be tricky.
Im not totally sure how this setup would work, Im betting that the front toilet has the one barrel valve. I would make sure both butterflies are close in measurement with filler gauges.
If its correct it should take gas like a brand new STIHL chain saw. Should see a best 60ft over a carb with gains of over .1 easy in 60ft alone.
Should also see a gain in water temp from launch to the stripe.. If its not building heat (WOT ONLY) the tune up needs work.
Also what kind of fuel system are you running or pushing to get the fuel to the barrel valve? stay away from any paper element filters, use a steel mesh in line style.
If your interested I can get you a good base line setup...