Not sure it's quite that straight forward. It seems to me that the key parameter is the depth of the horizontal float pins below the top edge of the bowl, actually the depth below the float lever arms. That's a function of the displacement of the float, the material used (buoyancy), position of the pin in the float body, etc. The 7 gram Rotax limit is their way of combining all that into something we can measure to determine good/bad with their floats.
I'm frankly tired of replacing my floats - my 4th set just went bad (almost 600 hrs on the engine). I'm certainly not impressed with the quality of the Bing floats, or rather, I'm highly negatively impressed.
I'm actually experimenting with the MS floats. I measured the pin depth of known good Bing floats and the MS floats and found that the MS pin depth was approx. 1/32" lower than the Bing floats which means a slightly higher fuel level in the bowl - I wasn't sure how that would affect engine running. I've just recently started test flying the MS floats. I've been approaching it carefully and only have about 5 hrs on the MS floats. Various power settings from low RPM to WOT, altitudes, attitudes, multiple take-offs, etc. So far I don't see any difference between the MS floats and the Bings. Power, temperatures, etc. all seem perfectly normal so far.
