Understand that slapping them onto an alpine setup will NOT be the same as a proper touring binding, even if you disregard the increased weight. Since the toe section of the Alpine Trekkers is just a metal ring to go over your boot, skinning cross-fall-line can be a little sketchy since the ski will tend to tilt with the hill instead of staying parallel to the bottom of your boot. When that happens, you might find your boot has a tendency to rotate out of the Trekkers, or rotate the trekkers out of your base bindings.
HOWEVER: what these are fantastic for is sidecountry and ascents that aren't too difficult. If you like to take a lift and then skin along a ridge out of bounds before making your descent for some fresh snow, these might be just what you need.
One might wonder why you wouldn't get just a beefier touring binding like the Black Diamond Fritschi Freeride Pro's or the Marker Dukes. They're generally a little more expensive than a your typical alpine binding, but around the same price as an alpine binding plus alpine trekkers.Final Note: You probably shouldn't use this if you have a large boot. These are adjustable length, sure, but if you extend it out a long ways (I have 330mm boots - 6'2") then you can tweak the central support (those screws). Sitting on the summit after two ascents I noticed that one of my screws had popped out!