I've never had to change any parts in the UM2 (Apart from teflon part, but you get a spare one), despite it being very easy for me to do so.
It could be possible that more extreme conditions (eg; Brazil is a pretty extreme climate compared to ya know, The Netherlands) give you more complications. We do test for that to some extent, but 'our' climate is tested the most, as every engineer at Ultimaker has at least 1 printer that they use to print with.
With regards to new stuff; We'd love to share it, but this is sensitive information. I do think that a new machine will not automatically make the old machines useless. Look at the difference between an UMO and the UM2; the UMO can still stand up to its younger brother with regards to print quality / speed, it just needs a lot more tweaking & maintenance.