I've calibrated my tanks both ways. Since my SkyView only takes one calibration curve, I ended up with the tail low curve after a major system rebuild.
It works fine. I know exactly how much fuel I have when I dip the tanks on the ground. I can compare this with my totalizer to verify quantity before flight, then depend on the totalizer for range determination.
When a tank or tanks get low on fuel, say 5 gallons, I watch them closely and cross-check with the totalizer. Until then, I don't really care.
When I did the tail level calibration, I could not cross-check the dipped level and totalizer accurately on the ground. In flight, due to the tank geometry, it was not possible to cross check until the tanks emptied below the gauge satuation level. Therefore, I often flew without the correlation.
So, i am OK with the tail low calibration and knowing how much fuel I have before departure for flight planning and cross-check the totalizer.
I think the g3X provides both, which is better in most respects.