Good looking grub, glad to see you didn't give up!
I installed a 4" therm and the first time I cooked with it the temps were crazy, I had impaled a piece of chicken, so now I just make certain there isn't anything in the way. I don't know if it's correct or not, but I figured a 2" stem might be too close to the door and not protude far enough into the cooking chamber. I learned that from putting a short therm on the side of my WSM and it always reads 10°-15° hotter than my grate therm.
In my BBQ books they reccommend marinading times of 4-6 hours, if you used a Asian marinade then you might have used soy sauce and that is potent stuff, I've marinaded overnight and the food was almost inedible, I now use light soy sauce in the marinades that call for it.
Looks like you've got plenty of smoke, what's it look like coming out of the top vent? Is it rolling or like boiling out, mine had 1/8" gaps where the top joined to the sides so I filled them with high heat silicone and my door leaks a little at the top, you might try closing the top vent down a little to keep the smoke in the chamber a little longer, did you use a little lump charcoal with the cherry? Also, when mine was new I didn't get much of a smoke ring, but now since it is well seasoned the smoke ring is there.
Enjoy your smokes,