I think the real problem with lowering a bike is when you don't get the proper spring rate for your weight and not adjusting the suspension setup properly. I did mine last March and already put more than 7,500 miles on it and lovin' every minute of it. My fork was sent to Traxxion Dynamics where they cut the springs and had it re-valved/re-sprung according to my weight and riding style and then they tuned it on their suspension dyno. Then, the rear was adjusted/tuned to match the front.
The only problem I've had was the very first time I went over a speed bump. Went a little too fast but never happened again after that. Also, I just have to watch out for potholes which are rare in our area.
One thing I can tell you.....I would never go back to stock setup. I really love the looks and the feel. It feels like the bike's glued to the ground yet very comfortable on long rides. Even 1,000+ miles a day doesn't beat me up. Again, I love it.
By the way, I do mostly highway so it's the perfect setup for me. Not that many twisties in MD anyways.
In case you haven't seen it, here she is.
You can see the fork better in this pic. I just want you to see what the fork looks like after cutting the springs.