you mean the sommersalt(sp?) defence??? ive never tried it but ive seen it tons... mos def a valid defence under the right circumstances... in one of ginos techniques the beggining is the same as the sommersalt technique with the whole turn and collapse the leg thing...
in wrestling we learned tons of defences... in some single leg takedowns they drop down and tuck the leg into the armpit and secure it with a tight one arm triangle thing then stand back up and bring the leg with you... at this point you can do many things, drive foreward, swing around, sweep, trip whatever... but we spent alot of time defending that moment when he has you trapped under his armpit standing up... there are tons of freestyle wrestling solutions... check youtube, you'll find lots... most start the same and end differently... but the theory can be used for striking arts too...