Re: Ratchet blocks
I have some of the Ronstan ratchet blocks, and I think the one with the cam cleat is auto-only. Even if you could switch it off though, that wouldn't be very convenient if you need to do it quickly.
The Ronstan ratchet blocks also grip the line tightly and can hold a lot more force than other brands... (I think around 60 pounds or so, iirc). That is great for saving effort, but if you need to ease the line, it needs to have either very little force on it (so the ratchet mechanism doesn't engage) or a lot of force, so the line can slip over the block.
There was a Practical Sailor review of ratchet blocks that listed their holding power - The Ronstan blocks were the highest by far. Other brands are designed to allow the line to slip back more easily, which I think would be preferable for a mainsheet.
(also the line type and size probably have a big effect on the ability to ease the line, so make sure the line isn't too big for the block)
Western Long Island Sound