According to actual tests of ABS, it does not slow you down faster than a braking system without ABS. It stops the brakes from locking up, and it does this by pulsing the brake system when the wheel sensors detect a difference in wheel speed. They installed ABS, not to make stopping quicker, but to help with panic stops where braking might be too much by, as you said, locking up the rear wheel or the front. Most sport bikes will do stoppies, where the front brakes are so powerful that the rear lifts off the pavement. But in reality, 70% of your braking is the front brake, and you want maximum performance from it.
whenever ABS kicks in, the pulse you feel is the brake being let off by the ABS system, and just like a normal brake, if your pull and release the lever rapidly, it will stop, but at an increase in distance. ABS is a good system, but on dry pavement, with no dirt, oil, or gravel, it will actually increase the distance of your panic stop.
An experienced or professional motorcycle racer, will not use ABS on his or her bike, as it can’t stop as fast coming into a corner, as he or she can with a practiced right hand.
I understand that there are many who rely on ABS and swear by it, and that’s cool. I, myself, would rather modulate the braking myself.
Charlie