Why do you need to measure distance? If you've been hitting the bags and sparring for awhile you should know distance.
It allows my jab to come out much faster and allows me to throw quick feints. cons are that my opponents are cautious about moving in and the delay between my jab/straight 1-2 combo is slightly longer.
I personaly enjoy using it. It seems to do a great job keeping most opponents at bay which is good but I'm not a southpaw so I don't know of the dangers from that. I do know from watching others at the gym if your short don't do it if your really tall it seems to me it helps more than hurts.
i am not a south paw but when fighting them i use it. when they tap my floating left hand i change it to hook to head, southpaw can use that too.
I have yet to be hit so far but I know one day someone skilled will smash my liver in when he slips my jab My normal style is White Tyson peek a boo in which I move around a lot, when I use the klitschko jab I fight a bit more static. And I noticed it's kinda useless when fighting people taller than you (I'm 6'2)
it doesn't matter which hand your using the floating jab with,,if your using this style of boxing you have to be confident relaxed & have great reflexes to see the Punch's being thrown its a great way to keep your opponent at distance they then have to work out how to get around it :vonnecunt
I sparred without it yesterday and I did a lot worse than normal. Started using it again and I could counter a lot