RIbbons (at least the LCY) are not as directional compared to other tweeters. excellent vertical and horizontal dispersion.
The Performance mids have more midbass output than the reference, but the reference has more detailed, more airy/transparent sound to it. The performance is a bit on the warm sounding side. Performance mids are able to extend higher because the cone is made out of polypropylene, as opposed to the magnesium-alloy of the reference (read: cone breakup).
Overall, the reference mids are better, mainly because of midrange distortion, accuracy, etc. The reference does take some work to get midbass output though. Which is why i'm using the performance mids as dedicated midbass driver. Best of both worlds //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif