That's all sort of a given. I guess my view of it is the difference it makes if for example you took my rig and put some 39-40" TSL's under it.....wheeled 5 difficult obstacles, then put Reds on it and wheeled the same obstacles, they are a little more than a small part. Of course you have to have the drivetrain or an obedient foot, or all yer driveline parts will **** themselves.
In summary, tires certainly can separate an average rig from a "that sumbitch'll go!" rig. Since this thread was about tires, that's the point the OP is at.....I believe he already has tons and driveline to support stickies, so the night and day difference between Iroks and sticky Creepies will likely be a pretty big difference.....at this point, all the other things to consider is not where he is currently.