I have a Harken furler system which has the double luff tape slots.. I have
never noted any advantage or disadvantage to have one or two slots.

I have two head sails that are of near identical size and have considered
trying this for downwind sailing, rather than a spinniker. In thinking this
out, a person would have to hoist both on the head swivel and then adjust
the clew pennant at the swivel on the furler drum. The most difficult part
would be to feed both at the sametime. Shouldn't be to difficult if you had
a pre-feeder for each (about 25-30 bucks each).

If your not interested in setting such a sail(s) then I can't see any
disadvantage to having the extra slot. For me it doesn't bother me since I
try to leave a half or full turn on the foil (to take the strain off the
luff tape).

Besides, kinda nice to have the extra groove incase one gets 'buggered up'
or fouled buy ripped out luff tape.

I'm not loosing any sleep over it. (well I guess I am, since it is near mid
nite)


--
My experience and opinion, FWIW
--
Steve
s/v Good Intentions