There's at least 4 7010/ 7120s pushing 40' drapers in beans in this area. Dealer says that two of the guys say they slightly under powered. Son has talked to a 3rd & he says the same.. Beans in this area will usually run somewhere in the mid to upper 50s & on occassion go into the 60s.
i personally think that you will be short on power. This year our 8010 had its pants full at times with heavy spring wheat with a 40ft. In more normal wheat it was fine. Soybeans i think it all depends on how tough your stems are. If you typically have heavier/tougher crops i would stay with a 35ft.
we do it on our 7010 we don't usually have the best beans. This year we were in the mid 40's and we still did 4.5 or better. It was a nice way for us to keep the machine full and match out 60 foot planter better. the 35 would have been a little odd we thought