Javier here. One of my Argentinean friends had one, after a two Transalps, AT, CBR, and a lot of smaller bikes. He says that the Sahara is a good bike but not strong enough, and the seat is like a torture machine inspired in the inquisition.
You are my friend so, I want you enjoy your travel and be happy, that seat will make impossible that things.
The NX350 is not the exacting smaller version of the NX650. It’s a mix between the XR250L enlarge engine and the NX650. That bike is not in production now, they are making the restyling version NX-4 “Falcon”. I don’t know too much about that bike.
Those bikes are only made in Brazil, so if you need parts or anything even in Argentina is not so easy. If you want to change your bike for some one more light easy, and comfortable, I recommend you: the NX650 “Dominator”, XR650L, XT600E, etc.
A big hug.
“El mejor remedio para la Boludez, es la Inteligencia…”