Well, I had a look at Groppel's book, and in particular at what he had
to say about the reach of a two-handed vs. a one-handed backhand.
It was not very impressive, to say the least. He merely *asserted* that
*he* didn't observe any reach advantage in the one-handed shot. Big
hairy deal. LOTS of very experienced tennis analysts have asserted
exactly the opposite.
Why is it that very few two-handed players are comfortable at the net?
IMHO, one reason is that MANY volleys are stretch volleys, and the
two-handed players aren't comfortable hitting the ball with one hand.
I'd expect the same principle to apply when they were forced to hit a
one-handed ground stroke.