Actually, I use Tam Valley Servos, which do have a separate power supply and controller, which I consider to be an advantage, not a disadvantage. It prices out to about the same cost per turnout as a Tortoise without DCC capability.
However, the Smail is functionally equivalent to using a Tortoise with a separate stationary decoder installed. I'm sure lots of people who have done that will reply.
Connecticut Valley Railroad -- A Branch of the New York, New Haven, And Hartford
"We don't stop playing because we grow old. We grow old because we stop playing." --George Bernard Shaw