i've tried it. it doesn't work for me, they're too strong from that position to get the cradle really in, especially if they're lock downing you. i prefer to go into reverse scarf from there anyways.
if it's a bjj guy, the likelihood of him really knowing how to sit out and fight from ref's position is minimal, if you want to break his turtle, grab the closest leg at the ankle, take a half nelson with the other arm and drive. you'll collapse and turn them around for an easy mount.
The wrestling moves are coming back to me now and seem good. My brother GIJoe6186 owns some guys with cradles latley. Was thinking of using a lazy man's cradle to play with if I can manage it next time.
if you can get a good cradle in, it's almost a guaranteed mount or taking-the-back. just make you sure you get them nice and stacked... only problem is if he has great leg fighting ability and stops you from taking the step over, or if you can't reach under his armpit to get his back turned to you.