Politely butting-in, I had the opportunity to hold both in my hands and put my belongings inside. IMO the pocket medium is definitely bigger than the original paddy, but in its own way. It's less "long" and more "tall" if that makes sense. Also I found I was able to fit more things in due to the increased depth of the bag. The paddy to me, is more triangular shaped while the pocket is more boxed shape.
The large one, I truly loved, but the color wasn't doing it for me (taupe). I'm patiently waiting for the large in blanc to arrive.
As far as the lock sitting on top of the bag, this is very true, but what I do is undo the zipper and bring the leather tag over and through the loophole, twice and then attach the padlock to it that way. This way, it hangs lower, is not in contact with the metal loop thing thereby protecting the lock from peeling. I do this on my hobo and I love it. If I didn't do it on my hobo, the lock would sit right on top and smush the bag down. That really bugged me till I figured out the alternative.