Just an update for in case this thread comes up on a search...
I got the medium fabric(dacron) and had the wings recovered in a day. The uncertified Dacron generic fabric did have a few small irregularities(a few snagged threads, but hardly anything to worry about). Nothing that I believe would be cause for any concern of strength or integrity. I'm really glad I went with the medium as it is significantly thicker. I went to just abut 350 degrees and it looks great. Got the rib stitching done quickly as well. Used flat chord and took my time with each stitch to ensure it layed flat on the top and bottom and then mashed them down even more by sliding the needle over them. All in all I was caught back up to where I was when my concerns arose in just a day. So for $100 in fabric and a day I am much more confident in the final product.