I can comment on the 1770nt 16r.  We have a lot of terraces and this planter will flex over any of them.  I have never had it quit planting or have a row unit out of hte ground yet and we have some steep ones.  On the ones that don't have a 40' slope I will plant 5 rows on the backside of the terrace and the other 11 on the front side(that is where the hinge is).  The combine will run leveler because it is actually straddling the top of the terrace.  We haven't had any problems because the corn has b een standing ok.

We bought a 3700 24-20 planter for beans this year.  I have only folded it out one time and can see that it is a lot slower than the 1770.  I also like the markers on the 1770 better than the kinze.

I'll let you know after I run the 3700 if I like it or not.  I think it will be okay though.  Won't flex like the 1770 but will still plant things fine.