All you engineers out there might know the answer to this: if you bring the sheets aft of the winches and bring them back using a block, doesn't that somewhat increase your purchase on the line, and wouldn't that in turn make the sheet handling at least slightly easier? Both manually and in the winch?
Actually, this won't give you any additional purchase, since the blocks are just turning blocks, which don't increase leverage at all. What they do is increase the friction in the system, which appears to give you additional purchase on the line, much like a ratchet block would.
For a block to give additional purchase it must be, or be connected to, a block that is moving. In a block and tackle, like found on many mainsheets, the bottom half of the block is moving with respect to the boom, and if you have three sheaves at the top and three at the bottom, you end up with a 6:1 mechanical advantage.
A simpler example is if you had a flat platform, with a block attached to a post in its center. If you ran a rope from a tree, down to the block and stood on the block, you would have a 2:1 mechanical advantage...since the block is moving relative to the fixed point in the system—where it is tied to the tree. You could lift yourself and the block by pulling up on the rope.
Now, if you added a block to the point where the rope is tied to the tree, and ran the rope from the block on the platform through the block at the tree, you can now lift yourself more easily, since you're pulling down, and can use your body weight to help lift itself, rather than just the muscles when you were pulling up on the rope. However, the mechanical advantage is still only 2:1.
To get a 3:1 advantage, you'd have to tie the rope to the platform, run it up to the block in the tree, and then down to the block on the platform. Again, you'd be pulling up, but it would be at 3:1 rather than 2:1 previously in the original example.
I hope this helps.