What specific concerns do you have?
The biggest difference is going to be that the rear suspension on the R51 Pathfinder is a coil sprung independent rear, with a body-fixed center carrier unit (differential); while the rear of the N50 Xterra will be a leaf-sprung live (solid) axle. The Pathfinder is a slightly bigger body, and will have slightly more interior room (and a 3rd row of seats, but that pretty well chews through available cargo area when they're in-use).
You said you know the differences, but just to review: there are a few years (only '08-'12, IIRC) when the Pathy had the VK56 V8 available, but they're rare and *really* retaining their value ... the Xterra had an MT (6-spd) available, as well as the factory e-locker in certain models. They both have the same front suspension, the same V6 and the same automatic trans. The transfer cases are virtually identical, but the Pathy has an additional 'auto' 4x4 mode that lets the computer decide when to lock and unlock the part-time t-case (the Xterra is more basic, being just rwd when the t-case is unlocked, and full 4wd when it's locked) ... with the Pathy, the 'auto' mode will be more like an awd, than a center-locked 4x4; but it does have the ability to be a fully locked center, as well. The Xterra will have slightly more options for factory axle gearing, than the Pathy; but neither is particularly well supplied in that regard, even from the aftermarket (though there are aftermarket ratios available for both).
All-around, the Xterra will have a bit better aftermarket support (here in the US, with most suppliers able to ship to Canada), but I'm not sure how well either would be supported in Central/South America ... I'm pretty sure the Xterra was only a North American vehicle, while the Pathy was sold more internationally (Europe and Australia, I'm pretty sure about for example); but I don't know much about the availability in the markets you're looking at, specifically.