The N series was Gleaner's first shot with rotaries. The first N6 & N7 had a lot of problems. The N5 was essentially the same machine with part of the processor closed off. Since the machine wasn't pushed as hard, the 5 was a pretty decent machine. When you got to the Series III Ns, most of the problems had been fixed but the company had given themselves a bad black eye on the reliability front. Later, they replaced the Ns with R5, R6, and R7. They were decent but still suffered from the engineers not having faith in the rotary concept and the cage and rotor were more complicated than necessary. Later, they came out with an updated R in the form of R50, R60, and R70. They were a bit better, but the 60 & 70 still used a PI processor that was complicated. The R50 had a PIII cage and rotor that was much simpler and eliminated the troublesome cage sweeps. In 1992, the R52, R62, and R72 were introduced and they all had the PIII processor and the fancy new cab. The Rx2 machines all used a lot of chrome and stainless on the high wear areas. The Rx5 machines introduced a newer cab but aside from some minor mods on shafts and bearings, there isn't a lot of difference other than more electronics on them.

Fine cut chopper takes some extra HP, but not a lot, as it is just driven by a single belt. I'd guess it could use up to 30 HP if you were in really tough stuff. Concaves are adjustable though, so you can retract them fully or partway to get the balance of HP and fineness of cut that will work for you.