Dug out an old physics text and looked up "pulley", hoping there might be something there that sheds some light on the situation.
There was. A diagram with a massless frictionless pulley (you gotta pay extra for those), and two masses m1 and m2 suspended from the ends of a string looped over the pulley.
Equations given for acceleration of the masses and tension on the pulley. Plug in m = m1=m2, an approximation to the situation at hand, and the equation for tension
T = g x 2 x m x m /(m + m)
(g is the gravitational constant)
gives T = g x m
e.g., tension on the string is seemingly constant throughout and
is equal to the split load. The top of the loop isn't a weak point.
So it would seem that if the load can be transfered immediately to two strands of a whoopie/loopie/x-oopie without being carried first by a single strand, Demostix's observation would hold.
I still ain't no mechanical engineer though. YMMV.