For what's it worth, I have done beans on beans on one field on a farm I rented for 11 straight years in a row, some other fields were beans on beans for up to 9 years in a row. As for a reduced yield, can't say I saw it per say, any reduced yield was due to limited rainfall, certainly not weeds or disease related. As for why I did it, simple, that farm had a history of limited rainfall and it was too risky to put to corn, beans did better with less moisture back then. That was long before the corn companies got drought tolerance bred into the corn genetics like there is today.
As for disease and weed pressure, I never had issues with any bean disease's on that farm ever, and for weeds, I don't combine weedy beans, I could manage to keep the fields clean, beans are far easier than corn and the window to spray is much longer with beans than corn, and my chemical costs were never any higher on beans on beans vs following corn, but that depends on your weeds your fighting on your farms more than averages.
If your concerned with a lower price, forward contract some of the bushels if your farms have a history of yield data behind it that have some sort of consistency.
I have no idea what your rent is, what your land payments are, machinery payments and the list goes on and on, but put a pencil to it, if you can lock in a profit on beans today, before planting, or corn for that matter, contract and plant acres accordingly.
I don't know the acres your talking, but you can rent a combine in the fall or hire someone to help you harvest beans, far cheaper than gambling on corn prices going up enough to provide a profit. Basically come up with a plan, and carry it out, involve your lender and make some hard decisions and worry about next year if it gets here, if your not farming next year its a mute argument.
If it were me, I'd not lose one nights sleep about beans on beans, multiple years in a row for that matter, since I'd done it many times before, despite what the experts say. The thing about experts is this, its never their money they are spending, their risk, their livelihood, their nothing, its only ever your ass hanging out, those experts have a paycheck to pay their bills with............just an observation I've noticed over the years. Best of luck.