I had one of the two front brake lines (racing setup) on my 96 ZX-9R split while I was down at Starved Rock. We had just run 71 through the twisties and turned around at the lodge, running them back again. Had stopped at that first parking lot right before the hairpin (going west). As I was pulling out I grabbed the front brake only to "casually" slow down. Started to pump it, as I was getting close to the road, and traffic. Nothing. Ended up killing the ignition and letting the clutch out (in 2nd gear) slowly to bring the bike to a stop. Since it was gravel I wasn't about to let the rear tire lock and dig in.
I got off the bike and saw the front wheel covered in brake fluid. Master cylinder inspection window showed it was empty. Had to ride all the way home to Carol Stream with no front brakes. That was a fun ride, and boy did habit kick in when going to stop. Kept wanting to grab the front brake lever. Lots of downshifting and rear brakes on the way back to slow me down. I can only imagine what would have happened had I zipped into that first turn at speed only to have no front brakes. I'm a good rider and all, but pretty sure I'd have been eating guard rail for lunch.
Ordered stainless lines, a bunch of fluid, and new pads all around. I'm not sure how much rear pad I had before I started riding that day, but I sure didn't have much left when I got home.
When I got my ZX10-R, and subsequently the ZX6-R, one of the first things I did was swap out the rubber lines for for stainless ones. They both got RBF600 fluid to keep them from boiling while at the track, especially for sessions at Road America.