I too think it's rather confusing. Why not make like 2-3 impedances? It feels like they have like five. 2 would be low impedance for ease of drive off of mobile devices (which struggle with high impedances), high for being able to use higher output impedance amps. Maybe a medium impedance option, but no more than that.

The way it currently stands, it feels like one is supposed to be the 'best', but that's not really the case, is it?

Then again, it seems like if you had access to any amp you could find, low sensitivity transducers offer the best. Most ToTL are low sensitivity, and when Audeze changed the 4 to 4z, many seemed to find a reduction in sound quality.