Tonight I did 7 sets of 100 on the pads and put the heavyweight resistance cords on to take the sting out of my punches as my fiancee was holding the pads for me and she is only 7.5 stones. Lets just say it worked, she had no problem holding the pads for me and within 15 mins I was completely burnt out and had a better pump on my shoulders than any weights session that I could have done. I am truly impressed at how much effort the shadow boxer takes and think it is a definite fast track method to improving speed and strength.
P.S. I've been wearing it backwards so even with hands in guard position I am under tension which can only help to train those hands to stay up at all times in the future, also I can agree with you that it will help correct punching technique as concentration is required to throw a straight punch as the cord is pulling down on the fist at the full extension of my reach especially when tired at the end of a good sesh.
If someone is holding the pads for you when using shadowboxer then the pads should be positioned at the end of your reach so that you have to fully extend the arm to hit the pad this helps for a better workout and also helps if the person holding the pads for you is a lot smaller like my fiancee 7.5 stone vs me 13.2 stone just to make sure that there is less chance of jarring or damaging the shoulders of the pad partner.
Once again thanks for a great product and your interest in my feedback 10/10
[note: Just to put the feedback in context Carl used to train for 30+ hours a week in Thai Boxing]