Hi Paul, yes the keel when fully lowered rests on the bottom of the keel box and there will be no tension on your lifting gear. From memory, when fully down the keel does not touch the forward roller. If the rain stops tomorrow, I will take a look as my boat is now out of the water.
As mentioned previously on the forum, I have a tell tale wire with two loops on it. One loop holds the keel fully up on the pin inserted through the loop. The second loop holds the keel halfway down, via the pin. This means I can have the keel up, halfway down or fully down with no tension on the lifting rope, dyneema in my case. To me, it seems a good idea to give the lifting rope an easy life and let the wire strop or keel box take the strain whenever possible.