There are many advantages that the 404 mogs have over the 60 and the 14 bolt. First off, How about 5 to 6 inches of clearance gains. Doesnt seam like much, but why are people spending the time to shave an inch off their standard axle.
Second, Turning Radius. I just got my front steering setup this weekend, and Believe it or not, My Longbed chev Truck with 42's will turn sharper then my STOCK 84 jimmy. And that doesnt include the extra turning I will get when I get the Back end as high as the front.(its sitting on a 10 bolt with 31's and a 4 shackle flip, the rear is sitting 17 inches lower then where it will end up.)
3rd Strength to weight Ratio(I know, that sounds stupid) But the 404 axle weighs about the same as the 60. But, it does weigh more then the 14 bolt. But, its where you want the wieght, down low. And they are much stronger then a 60, and the 14 bolt, even as strong as it is.
fourthThe C/V joints are much better then the single U-joint axle shaft. It wont give you that shimmy when hitting the gas while turning. They also used higher quality material on the axle shafts. Making them stronger. Also, the axle shafts are different diameters making the shafts the same strength.
Fifth Stock Cable lockers.
The only down sides I see, like mentioned ealier, is the pinion, and the diff offset.
And for me, it was almost as cheap to go upgrade to mogs compared to upgrading my 60 and 14 bolt. It cost $4500 for the mogs. And that came with, rear steer, disc brakes f&r, selectable lockers f&r, and high clearance diffs, and pinion conversions. I also went to a ford 205 on my doubler so I had to change that. It was around a $1000. And I also went to 42's with Hummer wheels. I got the wheels for $15 a piece at a local government surplus. And I found the Runflats on CK5 for a $100. So theres another $1360. (I would of had to buy the 42's anyway because of the 39.5's wearing out. So thats $6860 for almost everything. But, you have the subtract what I sold the stuff I had. I sold my, 60, 14bolt, doubler, and my beadlocked 39.5's for $3700. So that was only $3160 to go to the Mogs.
But If I wanted to upgrade the stuff I had, I would of spent around $1300 for the ARB in the front(to upgrade the Trac Lock),$375 for the 35 spline outers(to hold up to the stress of the biggers tires and the locker), probably around $300 to the disc brake kit on the 14 bolt, around $800 for a selectable locker for the 14 bolt(and thats if it ever comes out).
So thats $2775 for the upgrades, but I still have the single U-joint that doesn't let me steer worth a shiat, and I also get the shimmy when turned sharp, I get 5-6 inches less clearance, No Rear Steer, and weaker axles. And I also Have what about a million other people have.
I also beleive when narrowing the axles, if done right, doesnt make them any weaker. Daniel at killeraxles has had narrowed 404s in his truck and has not broke anything on them. Thats with a fullsize truck, 39.5s, and a 6.2 diesel. And if you dont think a 6.2 can break anything, lets put mine up against what ever you got(drivetrain wise) and I bet it could break it just as easy as a good running big block.