I took the doors apart over the weekend, but once I got them apart it was a tighter space to work in than I had originally anticipated, and it seemed like the overkill foam was going to be difficult to apply since it does not have the adhesive backing. I did install some damplifier to the door, and plan on getting some dynaliner and add that to the door as well since it has a sticky back and should be easier to apply; I will cut it into 6 inch strips or so and apply it in pieces. You could do the same with the overkill foam, just in strips, but it just seemed a bit of a PITA since you can't do the peel-stick-peel method and it will want to stick to everything going in.
However, since you are headed down this road sooner than I will probably get the doors done, I will share my experience so far with doing the doors, and you can post your impressions once you have done yours.
Door upholstery removal is dones as follows.
1) Remove the screws along the top of the door trim.
2) There is a small black screw rivet expander thingy that is located along the front margin of the door panel just anterior and inferior to the door handle, unscrew this about 3/8 inch and then pull the whole thing out as a unit.
3) There are two velcro pieces at the bottom of the door, working from the front gently pry the panel from the velcro. Do not pry the panel at the rear because there is a retaining clip there you might break.
4) Once everything else is free, the panel will only be held in the bottom back corner, slide the panel backwards to disengage the retaining clip.
5) Unplug the power window switch. (Just make sure to plug it back in when reassembling the door....Yeah, don't ask
6) There is a clear plastic covering the door hole opening, it is adfixed with this clear silicone like stuff. You can very carefully pull the plastic free of the adhesive and leave the adhesive in place or stuck to the plastic. When reassembling reuse the plastic and adhesive; I plan to replace this with construction plastic when I do the dynaliner because I ripped it on accident.
Now that the door is exposed, you can insulate away. So far what I have done is to cut 3" strips of damplifier and place them along the length of the door; realistically I should have placed the strips higher up on the door panel, I did them a bit low. I also placed a 6x6" square of damplifier near the back of the door panel right above the 3" strips.
When I get the dynaliner, I plan to pull the door apart again, and put 1/4" dynaliner over the outside door surface, and maybe even the insider fiberglass panel, it's really pretty light stuff.
With just the damplifier, I did not appreciate much of a change in the ride quality....maybe a little less door rattle over bumps, but not a real big difference. I expect that the dynaliner (or overkill foam if you want to use that) should help quite a bit. I have noticed a lot more noise from cars traveling next to me since doing the other soundproofing, and I expect insulating the doors should help in this regard.
First picture is just the door exposed for reference, second picture shows the damplifier strips in place.
Once I get the dynaliner in place I will post further impressions.