Fluorite lenses are incredible, but not a critical win until you get to high mag or up against the speed limits of your system. When it really becomes apparent is when coupled with VR stabilization, which can get you 4+ EV stops of speed. When the subject is that crisp, the chromatic aberration is significant, or, with fluorite, not. Interestingly, modern photography suites offer both correction of effects of lenses (e.g vignetting and pincushion) and chromatic aberration in silicon. Compared to where I started with a circa 1989 Nikkor 70-210 f/4 and film, the pictures I can take today are incredible. The real problem, for me, is editing down to a digestible number of eye-poppingly good shots. I imagine kids these days are thoroughly unimpressed, but I'm humbled by the incredible amount of engineering that has gone into photography.