Just to make sure we are talking about the same thing, I went and Google dtt:
http://www.eaton.com/RU/Eaton/ProductsS ... /index.htmI may be wrong, but the helical gears in dtt will actually make the Diff fully locked once it properly engages, and unless the wheel spin stops, it will stay engaged. This is what I referred to as "don't like". This Diff should be similar in operation to a torsen Diff. And also this is the reason I would not want one installed in the front.
Regarding breaking the Diff, it's always easier to winch it than wrench it. So if you know your vehicle limits, you won't break anything. I'd use the front locker in a stock Dana 30a only on mud, snow or ice, and even that, very sparingly, never rock climbing and never on tires bigger than 30-31 inch. There are folks breaking Dana 60, chromoly axles, etc all the time, especially in performance offroading. But they don't have a choice all the time to take it easy due to time constraints.
Bfg ta ko/ko2 are not too good on ice, I have had them for years. Excellent on pavement wear and tear, good in dry offroad, so-so in mud, with ko2 being better than ko. It's probably the best offroad tire overall that is also forgiving on pavement roads and not too noisy.
Detroit lockers are maybe the most reliable out there and they don't cost a lot either. I'd use those without a doubt on a dedicated offroad vehicle.
Onboard air is not really a must unless you have air lockers and popping tires out a lot, which means some really serious offroad. I mainly do some "safari" offroad, camping, some ditch crossing, stuff like that. Anyways, the liberty isn't made to be a true offroad, not w/o some serious mods, like tjkj's.
I'd be interested to see how the fan experiment ends up mass-hole, I think if you'll be OK with the hayden you may be fine with an ffd fan also. Oh, I'd also try the stant 190F if I were you. You can set the controller to start the fan at 205F and stop at 190F. I believe that's the interval on the flexalite controller (or it's 20F?).
Regarding your ecoboost, did you take into consideration the full gear ratio, that includes transfer case, transmission and Diff gearing?
DTT's are designed and work best in front applications.I ran one in my KJ for a little over 3 years and loved it.It was 100% invisible besides the steering wheel "returning to center" faster then when it was still a open diff.Was great for snow and ice since it was a point and shoot when in 4wd.Offroad you could step on the brakes a little and "fool" the DTT to locking,actually helped keep the D30A from breaking.
My buddy ran a ARB in the D30A for years and never broke the diff and he was not easy on it offroad.
Oh and be aware that OX changes hands every few years and here in Colorado they are not favored at all,it's more Detroit lockers or ARB's for strength and known reliability.
Last thing who ever stated that a F150 was 6400lbs is far off,before the aluminum body the heaviest(crewcab,V8,4wd) was actually around 5700lbs stock.