I've owned both the 22oz. and UL16oz model 856. Steady D, like you, I was intrigued by a six shot in a small frame. They do not have the internal locking mechanism.
Both had some QC issues. One had cut marks across the top of the star and, the other a sliver of metal around the circumference of the inside of the barrel. One was black finish; there is nothing nice to say about it. Stick to the matte SS if you get one, no complaints there.
They both functioned flawlessly up to the 200 round mark when I sold them. The UL would likely be a good carry. I'm neither recommending or not recommending. Having just had two Taurus made Rossi revolvers make their recall list, I'm a bit sour on the brand and any confidence in them. So I shed them all.
ArchAngel mentioned the Charter Arms Police Undercover, a six shot snub w/ 2.2" barrel weighing in at at 20oz. That is on my next to buy list. Since I own two other Charters and are happy with them, I'll be buying more. Currently own a 4" Police Undercover and an Undercover 5-shot snub, which is now my EDC.
Edit: Before I tried the 856, carried a model 85. If you like the 85 you'll like the 856. My 85 was reliable performer, no reason to think the 856 would be otherwise. You may have some minor annoyances in fit and finish like I did but that should be it. I may have come off a little harsh two paragraphs above, trying to be a bit more objective here, since I've never had a Taurus revolver that didn't function reliably.
BTW: Two out of three holsters I had for the 85 fit the 856.