Idk... I've rode in and helped with some leaf sas'es.... You can flex the right leafs out great. Yj on one tons and 42's rode like a dream on the interstate or backroads and flexed out pretty nice to.
Sure, but if you want major flex, link it with coilovers right? Go all out?
Leafs are simple and cheap.. And work..
And the d30; well it'll hold up to more than people think it will. If his plan is 33's and mostly a dd.. Than he's fine. If he's doing mud or slight rocks. Hell, I've seen a d30/8.8 rig run every trail at superlift ohv park on 37's locked diffs and not break... Yes, it has aftermarket axles; that just shows you have options to make it stronger.