I think you are wise to ask these kinds of questions.
browsed thru this thread pretty quick so i hope i'm not going over something that someone else said, but here is what comes to my mind. Alignment has been one of the biggest drawbacks to the IFS rigs i've owned. And tires these days are ungodly expensive. When you get to the point where your alignment won't stay in, tie rods wear out too fast, etc AND you love your rig and want to keep it, then you know SAS is right for you.
The other thing is if $ is something that you have too much of and you know you will get a lot of value out of seeing your rig and being seen with a straight axle, then go for it now. Endeavor to do it right the first time and keep it low. I've done several axle swaps and i'm still no expert...each time asking the pros for advice. You are lucky to have a Yota with a huge aftermarket following and a lot of people have been there done that already. But don't settle for less than what you really want, or yes the SAS will 'never be done'. for example:
I went with coil over and my Nissan Frontier rides super nice. Not like it did when it was IFS but not leaf spring SAS either.
I don't think you need SAS for the trails you run (right now). I saw a supersweet Yota with a doubler that was snow wheeling up in the Foothills one time. It was IFS but it had excellent control and a diversity of gears which made it go great in the deep snow.
On the other hand i'd stay off of super hard trails like Pritchett. Of the 6 or so IFS yotas iv'e seen on it, 4 were broken but i guy admitted he turned around to shepherd his 2 pals back out and i have little doubt he would have made it. I guess i'm just sayin' that SAS gets a lot less expensive when you confront expensive IFS failure over and over, from parts to alignment. This is just my personal anecdotal experience. I am not a 4x4 shop, never said i was, and i don't care for ARBs but i still have them.