Than,
I have had the T-Factors since April and also loved them till my season ended 7/10 with my injury (non waterski).
I too have a very narrow foot and also found that they run a little small and were tight at first, but they stretched out a little after a few sets and were great and very comfortable without any adjusting.
Good point on the flex, I tested the prototypes last Fall and the front to rear stiffness was crazy hard, very difficult to find the sweet spot and maintain it. Same feed back came from the others that tried it, so they were changed for production to be softer flexing front/back and now ski great. I also noticed the same thing with the tongue putting them on, you are correct, it will be second nature in a set or two.
As for the long bungees, here's what I did. I first reversed them, so the knot was on the top rather than the bottom, and kept playing with them and trimming them back till they were just long enough for me to loosen and get my foot out comfortably, but not longer. Removing this excess alone made a big difference. Then I used a lace end/keeper with a small hook like many bindings have, (mine were from O'Brien), at the top over the knot and used the hook to hold it under the laces below. Works great.
BTW, I agree that they will release, but on mine I replaced the heavier stock shock cord with a smaller diameter one since I broke my foot, (not with a D3 binding, and with regular laces, not shock cord), a few years ago when my front foot got stuck half way out during a crash. Rear released fine but the front did not, hung up right at the tightest point. (Of course I was holding on when brains would have dictated tossing the handle. Older and wiser now.) The smaller diameter shock cord has less tension on it and I think will stretch more easily when really needed to allow an easier release. At least it seemed to release easier during dry land testing. I tighten them no more than with the heavier cord and have found no difference in the feel or skiability of the binding. Probably overkill on my part, but don't see any downside and really don't want to repeat that again.