Haven't tried it, but I don't recommend using detergents with a built-in softener. Detergent cleans by stripping dirt off clothing fibers and keeping it in suspension, and liquid fabric softeners work the opposite way: by binding to fibers. If you combine the two, the net result is that at least some dirt will wind up staying on or in your clothes.
Also, one loses most of the softening power in the rinse cycle(s).