Here is my second painting on Pastelmat.  It's still trial and error for me at this point, but I'm getting used to the paper, and I like it very much.
Sushi Chef
19.5" x 15.5"
Soft Pastel on Pastelmat
People keep asking me for WIPs, so I tried to remember to take some pictures along the way so I could show you my process. 
First, I started out with a grid.  I laugh at myself when I try to grid, because I can never get the grid even, or to accurately match the reference photo grid.  And even if I had everything accurate, I don't have the patience to copy the boxes exactly.  So for me, a grid is more of a tool I use for the initial placement of the image, and then I draw the picture from the computer monitor.  I also correct and redraw as necessary when I'm painting.
For the grid, I took a few drawing pencils and made small marks on the paper.  Then I erased the marks with a kneaded eraser.  I used the pencil that erased the best.  I drew the painting with a pastel pencil, and lost parts of my drawing when the pastel pencil rubbed off, so next time I'm just going to use the drawing pencil. 
A note about pastel removal:  A kneaded eraser pulls up pastel very nicely on this paper, particularly if you're not trying to pull up a lot.  I found Q-tips effective when I wanted to remove a lot of pastel (meaning many layers).  A soft paintbrush is also effective.  I actually tried the vacuum, and was surprised at how ineffective it was (and my vacuum has a lot of suction!).
Here is my initial drawing:
I started painting the hat and face first.
Then the hair and shirt.
Then I finished the shirt and started the background.
Next I have a gap in the photos (sorry).  When I got to the hands, I realized you might like to see how I paint skin (I used the same method for the face, just didn't get pics of it), and thought to get a photo.  First, I redrew the hands with a pastel pencil (the drawing had faded by the time I was ready to paint the hands).  Next, I painted the local color of the skin, using probably six different pastel colors. 
Next, I blended that, then applied more pastel in the same manner, then blended again.  After that, I touched up with pastels and pastel pencils to define the hands a bit better (sorry, I got so into my painting I forgot to take pics!).
After that, I made corrections, removed things that weren't necessary, etc.  Here's the finished painting once again.
I am really getting to like the Pastelmat.  I like the fact that it is so soft, but I can get a nice sharp line on it.  It takes a lot of pastel, though not nearly as much as suede matboard.  This paper will probably replace La Carte for me.  I get similar results, but a bit better coverage, and blending is much easier on the fingertips.  As far as dust goes, I'd say I get less dust than La Carte, but much more than suede matboard.  I would use this paper for anything I would normally use La Carte for, and probably suede matboard and velour paper as well, with the exception of animals.  Once I get used to the paper, I may try fur again and reevaluate.
I hope this was interesting for you, despite the gaps in my photos!