Improvements to Merge and Channel Booleans

With all the great work being done with layers for render passes it would be great to see a couple of improvements to some of the nodes. For clarity it would be great to have a Addition and Subtraction added to the Merge node, I know addition can be done using the Normal blend with Alpha gain to 0 but this is not very intuitive, also I know exclude can be used to subtract but it clips at 0. Another thought could be to create a Multi Booleans operator (similar to multi merge) which may be a lot faster than a Merge as very rarely when compositing multipass renders do we use any of the functionality of the Merge node as passes are they're same size and require no transforms.