Been 100% rup corn for about 4-5 years now.  Have followed the 80% BT rule for about ten years now.  We put half rate of harness down before planting. 

We were somewhat of a holdout on rup Beans, as a local conventional variety was tuff to beat (profitable) for about 5 years after the Rup beans were sent public.  We grew some rup beans for seed before they were public.  Did a quarter here and there, and there was definately round up yeild drag for quite some time (maybe just bad genetics?).  Finnally found one, then another, and have been all rup beans for the last 5 years.   This year we put Treflan down preplant and were amazed at the weed control.

We do have navies in the mix, so not all our acres get rup every year.

For some reason this year Lambsquarters got smoked with rup as good as any other weeds out there, seems the last few years they were the weed in my back yard that was showing some signs of resistance (tuff to kill).   Waterhemp too, never saw waterhemp till after a few years of all rup.  Maybe pursuit took care of them???

Weve thought of going all conventional corn for a year, but am very happy (so far) with the program were running now.