I think firstly,
you cant really compare production IFS [cheap to produce, easy to adjust] with whats good and whats not, Most people now carry the "urban myth" of IFS and IRS through the poor designs of hiluxes and pajero's, even the 100 isnt great design, and the whole concept suffers in the public eye because of this. Look at off road racing for instance, they know IFS handles what is required, and they can make MASSIVE travel from IS, some trucks with 32" and 38" front and rear travel.
though the fact Walker Evans has built an IS comp truck, and doing another, and some other Rockcrawler guys doing the same, I think you will find once IFS has the amount of time live axle has had in development, and parts become more available that alot of things will go the IS route.
THis is one of the reasons I went this way early, as live axle had lost any challenge after the last few trucks I built, so was time to see what was out there, and see what could be done.
The adjustablity after a lift to factory settings or better, the on road handling, and longer trips the more direct and better feedback of the rack and pinion steering, as well as most 4wd trails here have been much nicer to drive with IFS I must say, and unless I was building a comp truck, wouldnt look at live axle for a car during the week, and trip/weekend wheeling vehicle again.
I am seriously considering the next day drive bush pig truck with IFS though, given some of the driving niceties, it has.