Floating elements are a good thing. They can make macro lenses perform just as well at infinity. In fact, many photographers buy macro lenses with floating elements and not the standards of the same FL. The down side is Macro lenses have smaller max apertures... at least the last time I checked they did. The point is that optical resolution is maximized and distortion is minimized from their closest focusing distance through to infinity focus. When I had my 55 Micro Nkkor I didn't own a 50 prime because I didn't need the speed. That lens was NICE!!