I put Progressive 412's on mine which dropped the bike 2.25 inches. DO NOT PUT THE SPRING PRELOAD ON HIGHEST SETTING! Holy cow I felt like a milk shake, LOL! I've got it on 2nd lowest setting and it's better, but still rather bumpy with only me on it. Hadn't tried with a passenger yet.
As for handling, you'll want to drop the front as much as the rear. If you drop 1/2 inch rear then drop 1/2 inch front. If the rear sits too low compared to the front, the bike will turn like a dog during slow maneuvers. My bike suffers from this a bit, but I like the slanted stance it has so it doesn't both me any.
I only understand what I don't understand.