I see you problem, because you want to test your new weights with existing animation keys, it's a pain in the butt to keep switching back and fourth from bind pose to your keyframes?
Normaly a character would be referenced into a scene, and so the weighting wouldn't be done as you are animating, but tested first. I do all my testing before I build the controls on the basic FK skeleton.
However, to make this a little easier for you, you could make 2 simple shelf buttons, GotoBind and LeaveBind.
//GotoBind
DisableAll;
select -r joint1; // Change joint1 to a joint in your skeleton
gotoBindPose;
//LeaveBind
EnableAll;
Copy the above scripts to your script editor and drag them to 2 shelf buttons. When you want to paint weights run the first script, which will put the skeleton into bindpose for you. To turn back on the controls, run the second script.
Richard