Its a nice and clean truck you've got there! Good to see some Trucks/Hiluxes inbetween all the Tacos.
If you shold SAS or not depends on where and on which surfaces you're planning to drive on, how much money you want to put in and if you want or need reability. The stiff axel works great in the rocky and muddy terrains, while the IFS is just best for the on-road (as I guess you know).
The comfort on road is the most important for me as of now. No chrushed drive axels, no fear of cracked diff house or 3rd member - nothing. Just counting kms. In time it will get an axel swap as i'm planning a trip down Europe, through nothern Africa and up eastern Europe and to do that I need reability. If a leef cracks - no problem! "Get the blanket sailor and lay between the frame and axel".
Also there is _a lot_ of spare parts, upgrades and so on for the stiff axel. Marlin Crawler, All-pro, Trial-gear, Low Range Offroad, Longfield superaxels, Sky manufacturing etc etc. + the ability to have a Toyota E-locker (n/a for 7,5" IFS diffs)
'94 Toyota Hilux - 1KZ-T/3.0td swap, 37", 2" OME, Safari snorkel, Recaro
'82 Toyota LandCruiser HJ60 Arctic Truck - 1HZ, 12" longer wheelbase, 44x18,5x15, OME, Safari snorkel, 3" exhaust, 2x ARB AirLockers