IMPO, speed is key. If you totally suprise them you may not need to wiggle that foot out.
But I am becoming a fast believer in keeping that foot in there DEEP under thier shoulder blade for extra leverage on the fulcrum.
I would REALLY like to have both legs across. But as I said earlier speed is key to this technique. There is a possibility that he locks his arm up and defends. Maybe he grabbed his own arm, maybe he grabbed his shirt or gi. Whatever the reason you cannot fully extend the arm in that explosive and fast technique. It is at THIS point that I will buckle down a bit and free that foot, place it across the chest and go for the traditional straight armlock. There is no doubt in my mind that it is the strongest position in terms of control. And I prefer to have control of my opponent whenever possible. Let him lock up. I will situate myself and THEN work on breaking his grip apart.