No one seems to like my answer to this question, but I have some experience and an opinion so here it goes.
I think a 5.0 sounds like a butt load of fun to drive. I may do one some day for that reason alone. However, from my experience any engine conversion high dollar or budget that I have built or owned had some reliability quirks. I know some people have figured out those quirks, but it has been a learning curve and definitely not overnight. Heck, even my hemi swapped lj that a shop performed and I had 18k in receipts from the previous owner had its quirks that affected reliability.
That being said, there is a reason i held out for a 4.0 manual everything ranger. I looked high and low for one actually. The 4.0 is adequate. With my 5.13s and 35s it does great on the highway, even on the passes. Plenty of power. Even for towing heavy stuff it is fine. It's not a hot rod (definitely not a hemi lj) but it is fine.
I don't think the swap is worth the reliability compromises and the sheer amount of work.
A doubler is definitely less work. I enjoyed the d and d doubler I installed in my explorer. It was fun to build it too. However, there definatelt is a good amount of work. Mounts (engine and tranny), shifters, moving cross members, welding in the filler plate, moving the gas tank, driveline lengthening and shortening, speedometer issues, etc.
When it was all said and done, I added up the cost and the time and I think it would have been easier and within a few hundred to go with an atlas instead.
That being said, I will not do another doubler. I will do an atlas and be done.
I know Matt said the doubler was more significant than the sas for him. For me, I would much rather have (and do have on my ranger) the solid axle first. For ride, reliability, suspension travel, etc. the solid axle is the single best mod I have done to a truck and I love it in my ranger even without a doubler and lockers. However, my ranger went from stock to 35s with my sas. It wasn't like my exploder where I modded suspension multiple times and was running 34s any way. I did the ranger right from the start.
All that being said, my ranger may never get an atlas. I can deal with smoking the clutch a little in the really rough stuff for now. Besides, when it's that rough I risk having a crushed pop can body like my exploder. I don't want that.