I only have the older ones but I've lately been thinking that the newer removable valve may be a better way of building them because of the ease of resealing or even replacing a whole valve if you have to. The power on the new ones is the same as the old ones, pretty much. I've heard the replaceable valve guns are harder pumping due to having one spring rather than two but there is much written about changing it over to a two spring system on your own for easier pumping with no loss of power.
Wait... What?Who are you and what have you done with David?LOL!