I think it is best to have both ratcheting blocks and one with a switch to turn on or off. In light breeze we turn one off but in anything above about 7 knots they are both one. This will help the crew immensely.
+1 on this. I actually like having the ratchet on the forward block (one on the beam) in light air as I find it lets the spin go smoother during gybes.
Also, no one mentioned gloves. Make sure your crew is using some sort of hardware store glove like this:http://www.ebay.com/itm/Flex-Tuff-Work-G...=item337aaeb7a2
I cut the thumb and first two finger tips off, helps me deal with shackles, knots etc. These kind of gloves have WAY more holding power then your standard over priced sailing glove.