You can send it in for a tune up. The "new style" autotrigger is just a small ball bearing and a spring that retains the cam in the frame. Very similar to the safety in a lot of frames. An o-ring on the screw that attaches the lever to the pump arm has the same effect. Problem is, it is an extra step in the manufacturing process. It isn't a simple bolt-on mod, the frame is drilled to accept the bb and spring. Unless you are having problems with the cam shifting and binding the trigger i wouldn't worry about it.
As for other refinements, the vertical ASA being machined as part of the main body and the cocking rod knob looking slightly different are about the only other changes that have come along.
If it ain't broke, don't fix it...