First i want to say Hensley IMHO makes a QUALITY product.
BUT I don't think every truck NEEDS one. I have a air bag kingpin, honestly don't think it helps a HUGE amount but it does some. I had bags on my last DRW with similar RV setup and it rode great as does my current DRV with about 6k pin at 25% of the RV's weight. Just don't see how my setup could ride any better.
I do believe my Factory rear air ride helps along with the kingpin air bag. The key IMHO is the fact I have plenty of pin weight.