I doubt that in a home-invasion situation that the bad guys will press an attack once the first round is fired.
I don't disagree
But what if they don't?
and they surely don't 100% of the time.
What if you let one loose and miss? (very common in a high stress situation?)
Now you're in trouble, and the bad guys know it (If they saw what gun you had).
Why would you unnecessarily limit yourself?
You can't insure against everything, so you make reasonable precautions and buy that level of insurance. You make a decision not to buy insurance for things you deem out of the realm of possbility, or the cost is too high for the minor gain achieved. (ex. you don't live close to a river, so you choose to save the $1000 a year on flood insurance because the possibility of you being flooded is very small. It certainly may flood and you might lose out, but you made a conscious decision that the risk is low and you can live with it). People do this every day in all kinds of decisions.
You have already made the decision to defend your home, the risk is too high. You've choosen to obtain a shotgun as a HD weapon (an excellent choice, much better than a handgun) and now you are choosing which weapon to protect against your level of risk? So, a coach gun costs about $500 (cheapie entry model), and a 870 or an 1100 costs about $500. So, cost isn't an issue. Why would you limit yourself to higher risk level (only 2 shots basically) for the same amount of money?
Now certainly there is some level where the additional "insurance" doesn't pay off. (in one decision you already decided you didn't need a semi-auto 50BMG rifle with 50 rounds because that scenario's risk factor is too low to be worth insuring. (For most people
). But adding a few more rounds to the platform for no additional money seems like a slam dunk to me.
It's like if I have car insurance. for $1000 I can have $100,000 worth of liability insurance. For $10 extra (learning the manual of arms for a pump/semi-auto), I can have $500,000 worth of liability insurance. For the low additional cost, isn't that worth it to insure most situations? (and to continue the analogy for $500 more I can bring it to a million, well maybe that's not so worthwhile because how likely is it that I run into a million dollar car? (unless I"m following around Britney
)