Lockers, of any kind, will always want to push you in a straight line, which in my experience, will often push you off the line you wanted to be on, or making it hard to take the line you want. While this is less of an issue for the experienced wheeler, it can be a PITA for the novice/intermediate wheeler, and for those spotting them, as they don't have seat time necessary to compensate for this. I wheeled open diffs for almost 15yrs, and after 15yrs of running lockers, I still prefer wheeling an open diff as the default setting, for me, a selectable locker is no different than dual cases,and engage them only when only when needed.
As Gnarly mentioned, trutracs are good, but getting them to engage when needed can be an issue, if you had dual cases, or an auto trans, it would be better, as you can use the brakes to engage it without stalling, a hand throttle can help with this. If it is one or the other, I would go with a standard mechanical over the trutrac.
A new ARB isn't your only option, the Toyota e-locker is also available, and can usually be found used for about $600, though it does take some slight modification to the stock housing to install it.
I see, the engaging part does seem like a pain with the trutracs. I am just a little skeptical with the standard lockers and how they engage/disengage while driving, unnecessary tire wear, it always being on, etc.
Aside from locker talk, you mentioned dual cases. I have done some reading and talked to people I know who run a single 4.7 case and I just cant get over the fact of how slow you are going in 4 lo. I would want to run dual 2.3s over a single 4.7 no doubt. What exactly does marlin sell that I would NEED to do a dual case set up? And where could I find another set of 2.3 gears new? I am sure I could find some in a parts/donor car but lets just say I wanted it new.
Maybe you guys could give me some options on what I can do to make my truck a better wheeler with open diffs. Snowtoy mentioned a dual case/lower t-case gears. Anything thing else? Like I said my truck is basically stock. No lift, 31 inch tires, rancho shocks all around, stock diff and t-case gears. I bought a marlin rear bumper last week thats coming tomorrow
which I am happy about. I like what you said Snowtoy about preferring open diffs overall. Makes me reconsider buying a locker right away.