More convenient yes, MORE secure, no. I agree with C. Burch, you are adding another potential failure point, period.
So, a single threaded attachment that is frequently unscrewed and rescrewed and subjected to torsional stress during use is going to be
more stable than a threaded attachment with threadlocking applied plus a clamping screw that's not subjected to unintentional torsional stress? Sorry, no. Yes,
in theory, two connection points vs. one means two possible failure points rather than one. If you were doing a 350' free rappel (I've done one), would you prefer to hang from a single loosely tied knot, or a pair of 8,000-lb-rated carabiners connected in series? The latter has
two possible failure points vs. just one - it must be less safe, right?
I can tell you that I spent over a year with the single lug connection, first as a FastenR-2 then FastenR-3 connected to a tripod socket, then with a FastenR-T1 connected through a Manfrotto RC2 plate. I would frequently find the FastenR slightly loose - probably at least once per week. It never loosened sufficiently for the camera to fall - but that's because I quickly got in the habit of checking the tightness of the lug several times a day. In over a year with the FastenR-3 Loctite'd to a Kirk clamp attached to a body or lens plate, I have never had anything come even slightly loose. I know which sounds more failure-prone to me, and I'm not a fan of letting untested theory outweigh empirical fact.