I think that the great thing about the original wool cover was the "less is more" approach.
But if your gonna go with a suit you need to improve it. You'll notice in video games where characters are suited that a lot of time is put into aesthetics, possibly the greatest example comes from bioshock.
The thing with suits is that they completely cover the character, you can't form attachments to their faces because the suit makes them faceless (in the picture). So people make attachments to the suit itself. Which means that you need to put in the kind of detail that you would put into a person.
Look at the bioshock suit and ask yourself what kind of emotions it invokes in you. One is definitely fear, which is appropriate considering that's how you should feel when you see one in game.
The problem with your suit is as far as emotions go it is almost completely sterile. It doesn't evoke very many emotions.
For example, since your story takes place in a post apocalyptic world then I would slap one of these somewhere on your suit.
Also you need to keep in mind the angle from which the shot of the picture is taken from. If you look at the bio shock one (a common angle in all video game pictures) it makes you feel small, heck, even smaller then the little girl. Which only further induces the feeling of dread and fear.
Here's another picture you may be able to relate the story to more easily.
In this one you do have an image of a suited character in a wasteland. This suit image was created by crytek and the pose has become widely copied, namely the main character facing into the distance with the face halfway turned towards you.
I think that having your suited character mimicking that pose would be appropriate.
It is good for the following reasons:
It introduces your character but it does not "over expose" them. Meaning that they see the character but they also see the background. It wasn't until the third time I saw your suited character that I noticed that there even was a background just because the character seemed to dominate my attention. So the trick is that by having your character face a certain direction it will force the audience to think "where is he facing?" and so they will look out to the background.
By having the face of your character turn back slightly it makes it seem as though he/she is looking at us which captures the readers attention much in the same way as the first paragraph of a good novel should capture the reader's attention.
I also have one more idea. You know how the character's illustration is framed by a hole? Replace that hole with a round window, the more rustic the better. If you combine that with the other idea I had above, along with the current color scheme of the rest of the cover it will give the impression that the reader is INSIDE the shelter looking out at the main character who is looking back to them while at the same time getting ready to leave. Perhaps invoking a feeling of a found farewell in the reader.
You see, by making an awesome illustration you can start to mold the feelings of the reader and start to tell the story before they even read the table of contents.
Think about the bioshock and the crysis 2 examples. The Bioshock cover tells you that the story is gonna take place under water, that those two on the cover will be central to the story, but the big one is probably going to be an antagonist. The leaking water and rusted over structures as well as the darkness tells you that it will probably be a sort of post apocalyptic scenario.
The crysis 2 cover tells you it will be in new York city, the brightness of the background and the non confrontational nature of the suited character tells us he is a good guy. The explosions should be pretty obvious, that the city is under attack. The rifle in the suited character's arms says he is a soldier. And since he is the only one in the image then that means chances are he is the main character. Which suggests that he will be fighting the invaders (which are cleverly absent from the image), that he will have a central part in this story, and that he will be a hero.