I've owned 4x4s half of forever... Yeah, you absolutely want manual hubs. Partially because of the ability to use low range in 2WD and partially because they WORK. And I strongly prefer manual transmissions in my trucks.
But having said that, I'd like to argue AGAINST 4x4 or manual transmissions for playa mutant vehicles.
I've never even come close to needing 4WD on the playa. Ever. I believe that you will gain nothing but extra deadweight to tow over the mountains and extra unnecessary expense if you have to fix anything or buy manual hubs. Also, in general, 2WD donor vehicles are cheaper.
I once had a small mutant, based on a riding mower chassis, that had your super low gears and a clutch. A manual trans on a playa mutant is a real pain in the ass compared to an auto, just like it is in stop-and-go traffic jam situations. You don't want to have to always be on the damn clutch. It does work and you can do it... but I wouldn't intentionally choose it again.
On the flat, level playa you don't need low range. The slippage in the torque converter gives you all you need.
The auto will always be in First at playa speed regardless of where you set the shifter. Just drop it in Drive and forget it.
That's my opinion.
"Whaoomph! Whaomph! Burbbleburbblepattpattpattpatt... WHAAAAAaaoooaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa........!!!"
Top fuel dragster, by Elliot Naess