Nothing in life is risk free. All we can do is try to influence the amount of risk we are willing to bear. In a civilized society, we trade risk for money. It's a good thing too, because within the realm of home ownership, it creates a need that keeps us employed as inspectors.

Of the three options that I posted above, door #3 is the most risk and least cost. Door #1 is the least risk and probably the most cost. Door #2 is somewhere in the middle. The homeowner needs to decide how much risk he/she wants to bear and what it's worth to him/her.

The question, asked by the starter of the thread, is The appropriate professional who is qualified to answer that question is a structural engineer. Others are just guessing, and believe it or not, in NY State are probably committing a felony! (by practicing engineering without a license).

Side comment/Mini-rant: Most inspectors seem to have no trouble recommending various trades people repair things they find wrong in a home. Many inspectors (but not all) routinely call for trades people to come to the home and "further evaluate" things, which is really just "passing the buck" -- the inspector should evaluate the condition and call for repairs. I think it is appropriate for an inspector to call for further evaluation by a qualified trades person when they tell the client "this is an unconventional system that I'm not familiar with or qualified to inspect. I recommend you have a qualified xxx come in and inspect it for you".

When it comes to questions about the adequacy of components of the structural system in homes, I frequently see comments from inspectors that they don't want to "waste their clients money by calling for an engineer". What's up with that? If your kid's not feeling well do you take him to "uncle joe" so you don't waste your money on a doctor (assuming, of course, that "uncle joe" is not a doctor)? Many times the doctor just says "take some ibuprofen, drink fluids, and get plenty of rest". Was that doctor visit a waste of money? What if you decided not to go, and it was something more serious?

P.S. - If it was my home, I'd choose door #2 and be done with it. Twelve feet is a LONG span for a main bearing beam, and have you thoroughly checked that beam for excessive knots and checking in addition to the more typical things you look for such as rot, and notching? I'd choose door #1 if for some reason I really didn't want a column there (like maybe it would be in the center of my pool table), or if I wanted added peace of mind that one column in the old location would be sufficient. And I'd choose door #1 if there was any evidence of structural movement.