It kills me that guys pulling RV's will cite better mileage or reduced maintenance with a 4X2 as the reason to purchase the 2 wheel drive. Both are generally so slight that as to not be a factor, yet guys will spend the money to pull a $50-100K RV and talk about saving half an mpg by forgoing a 4X4. Stepping over a dollar to pickup a dime in my opinion.
Nothing wrong with an IFS 3500. I have had 6 of them and I pulled at or over GVW with all of them and never put a dime into the IFS. This is a 30 year talking point arguement from 1988 when GM went IFS. If you want to look at a struggling front end design, look at Dodge/Ram front axle set up since inception. Now that is something to have a conversation about. Simplying having a solid front axle doesnt not mean it is bullet proof and having IFS does not mean it is a POS.