I was under the impression that V tails don't reduce wetted area......
There is a number called tail volume coefficient. Distribution
of this area in a V ot T planform results in the same wetted area.
You might make the case that the V tails are of a higher aspect ratio
and "better" but you also have to account for crosswind performance.
The max crosswind you can land in is determined by rudder effectiveness.
(I'll skip the wing low attitude/long wing problem) A V tail reduces up
elevator authority as the crosswind component grows. So it appears that
a V tail gliders minimum approach speed go's up as a function of the
crosswind. There may be insufficient "elevator" area or pitch authority
to flare as opposed to straight line flight where both elevons/elevators
will be moving "up".

Scott
I would like to add,
If the V tail has a fixed stab the moving elements have to be large, because
of that, the airfoil can not achieve its aero dynamic potential. In the
case of
the HP 18, the hinge line at the root is at 45% and at the tip at 55%.
With
an all flying V tail this could be improved.
Over all the T-tail is the most effective, as each element can be optimized
for the function in term of size and aero dynamically generally and
specifically
having different airfoil for the Horizontal and vertical stab.

Udo