Options are always good. I know a few people who have bought inserts for their shotguns to shoot a variety of calibers in their shotguns beyond just the normal 12 gauge. Not sure how accurate these things can be but being able to utilize an assortment of ammunition is certainly beneficial.
I have a group member that has done something similiar with his Glock. Having extra barrels and magazines allows for interchangeability between 40S&W and 9mm using the same frame. Add a .22LR upper to the frame and now 3 calibers can be shot out of one gun.
A loyal reader sent in some information to me of a very similar nature. A picture is worth a 1,000 words:
In this case four calibers in one gun.