Two is better than none, and of course there are various types of "lockers", but I'd question the strength of an unlocked LT230 with f/r lockers. Perhaps someone can comment on that.
It's more than capable of handling the vehicle itself in 2WD. The problem is wheels suddenly spinning or suddenly stopping. With an axle locked, you're opening up the potential of a shock load generated by
two sets of wheels, tires, and brakes.
On my DII, that's around 250 pounds of rotating mass, give or take. I can't remember the exact number at the moment. That's
not a small amount.
So long as you're not an idiot, you
should be okay. That said, if you pop that thing, it's certainly going to be a hell of a lot more trouble to fix than an axle differential, and odds are you aren't going to make it home. It'll take the same amount of stupidity that it takes to break an axle differential, though; and quite a few have never broken one.
The same forces can be applied in other ways, though; even with a locked center. It's just less likely.
If you've got the time and money, by all means make the swap. The vehicle looks nice enough to justify it. If not, either learn to drive properly, or stay off of rocky terrain with highly variable traction surfaces. Obviously, it would be best to swap the case, but it's not explicitly necessary to enjoy the vehicle.
It's better to go off-pavement and enjoy a compromise, than to focus so much on perfection that you never go off-pavement; it's just not ideal, and you need to be more careful and know your shit. These things aren't nearly as fragile as people make them out to be, but anything can break.
When that "anything" is hiding in the very heart of a complex transfer case, however, it's a good idea to check yourself before you wreck yourself.
Cheers,
Kennith
