I got one for $4.99.
Taco Bell's website actually lists the Chipotle Chicken Stack as being about 30 grams bigger than the Triple Steak Stack. It was definitely filling and I appreciate the chain using their normal chopped chicken instead of the shredded chicken they've been going with in so many of their new menu items. It makes for less of a mess, which could have been a real problem for this sandwich.
Nutritional Info - Taco Bell’s Chipotle Chicken Stack (318g)
Calories - 780 (from Fat - 320)
Fat - 36g (Saturated Fat - 12g)
Sodium - 1730mg
Carbs 62g - (Sugars - 11g)
Protein - 54g
Q's Note - I ended up trying this one as well and don't have much to add. I found it notably less salty than the Triple Steak Stack but it still needs something else, like maybe the cup of salsa Darius suggests. Also my flatbread wasn't nearly as burnt as yours but I think my chicken pieces were smaller: