With a POD of either a lack of Portuguese success in their 1801 invasion of the Misiones Orientales or a British conquest of the Rio de la Plata region in 1806-07, Rio Grande do Sul would be a smaller Brazilian state than OTL. It would be located in the eastern and north-central portions of OTL Rio Grande do Sul, and the rest (i.e. the Misiones Orientales) - as well as Uruguay - would belong to Argentina (as long as there's no Liga Federal and hence no Cisplatine War). Even in this rump Rio Grande do Sul, as far as I know, there would be gauchos in some places, though probably not as widespread as in the Misiones Orientales to the west.
Would such a territorial change for Rio Grande do Sul have led to a radically different Brazilian army, given that OTL a large proportion of Brazilian troops came from that state and conflicts involving Brazil have taken place there? If so, would the republican revolution overthrowing the Brazilian monarchy, and the tenentes revolt even later than that, have taken a very different course than OTL?
And would the rump Rio Grande do Sul have not had as militaristic or positivist a tradition (and later on also leftist and personalistic politics - e.g. Vargas) as OTL Rio Grande do Sul? In other words, would the rump Rio Grande do Sul act a bit more like Santa Catarina or Parana states (or at least in between those and OTL Rio Grande do Sul)?