170r has a lot more metalwork, and a lower profile. it also will have a nicer mechanical trigger as i believe the one for the etha2 was a slide trigger instead of a rotating trigger?
also, the 170R has a board with a screen on it, so you get a much easier time of changing settings / having a game timer, getting error codes back from the gun, that in itself is probably worth quite a lot.
Also i think the bolt is in-fact a revision in the 170r which should be slightly gentler / more consistent with paint.