Pump and Semi-Auto?

In our May issue, we reviewed the TriStar TEC 12, a shotgun that can be either a pump or a semi-automatic. This is very cool, because the only other shotguns I'm aware of that have such capability are the SPAS-12 and the Benelli M3. Needless to say, both are significantly more expensive than the $689 TEC 12. But the capability to be pump or semi-auto also got me thinking…

Personally, I prefer a pump shotgun for home defense because I'm simply more comfortable with it. Others could say the same for a semi-auto. What I'm having a bit more trouble with is when I would need or want to have a shotgun capable of both types of operation?

The most obvious scenario is a failure while in semi-auto mode, when you could switch it to pump to clear the malfunction, but malfunction clearance should be a part of your semi-auto training and it probably takes longer to switch to pump operation (barring a lot of practice) than to just clear it as you would with a semi-automatic. Our Shotgun Editor mentioned the TEC 12 can shoot any type of ammo reliably, since it can run in two modes. This is indeed useful if you only have one shotgun and plan to use it for multiple roles, but I'd rather have a dedicated home-defense scattergun and another for field/sport purposes. That said, one $689 shotgun is still cheaper than two $350 shotguns, and that presumes a fairly inexpensive model for field use.

The TEC 12 has a ton of other features that make it a great choice for home defense, but I wonder if I'm missing the big picture when it comes to the dual-mode system. Do you have any other ideas as to why this is useful?