No question whirligigs are great tools for teal. Even down here by the Gulf teal are generally as tame for them as yankee mallards. And, of course, if you set up in the right place, they, other decoys and calls are all unnecessary for any waterfowl.
But day in, day out, I like my chances with a teal call or at least a squeaky, squawky mallard call a whole lot better. Some passersby will bank on reflex, just like their big cousins, and others that have plainly pushed of the spinner or setup can be talked back into messing up, just like their big cousins. That's not saying they're nearly as susceptible to good calling as mallards, mind you, just that calling teal can be well worthwhile. 'Least it has in my experience.
If you think I'm wrong, you might be right.