Did you decide whether or not you're staying with IFS? I was thinking about it when I read it and IFS has a lot of benefits over solid axles in pretty much all categories other tha. Off road travel and durability. But then I was also thinking a solid axle would certainly be longer lasting and easier and cheaper to repair if and when the time comes.
Also, Ford and dodge both continued to use solid axles on its HD models. IMO chevy messed up ditching the solid axles all together and if I was in your shoes I would swap it out if the funds were available.