The comments here are much the same as I have heard elsewhere. I have gone ahead and ordered the leather one from Champion's Choice.
The main reason for the change was that I found that the canvas coat just simply did not give me real good support in the offhand position. For the other positions, it has served me well. After doing HP now for about a year, I can fairly regularily shoot in the mid to high 190s in my rapid fire stages. Prone 600 is staying in the low to mid 180s - due mainly to my lack of wind reading experience. I may still use my canvas coat for all but the standing positions but that is to be seen. It is fairly cool with a zipped hooded sweatshirt under it.
One thing I learned by talking to the nice lady at CC, I am 6' 2" tall and thought I would need the "tall" sized coat. She talked me out of it saying that the tall sizes shouldn't be worn unless you were at least 6' 4" or 6' 6". Otherwise, the sleeve length could get in the way. Since my knuckles don't drag when I walk, I thought that was good advice. I'll see when I get the coat in the next couple of days.