Here are the pictures for yesterday. Please excuse the filthy couch. Once you have a toddler, you tend to give up on a sueded cotton finish.
I even carried a little extra just for the sake of showing you what it can do. Well, that and it was cold yesterday. If I were to leave the jacket out, it would have been about 2/3 of the size shown. I also threw in a granola bar and an english muffin with jam. The second (?) picture should show that I put my shoes in the bag first, staked and to the side, then put my clothes in next to that. I then threw in the jacket and patch kit. I always leave that at the top in case I need it.
I did my 50 mile round trip Arlington to Dallas commute on this setup, and again, zero issues. I've done the rack and pannier thing and like the saddle bag much, much better.
In regards to clothes wrinkling, I've never had a problem with it. Granted, I wouldn't put slacks and a button down in there, but that's kind of a given. But I've not had any significant wrinkling issues after 25 mile rides with shorts and a t-shirt.