This only works if you can guarantee that the changes are not intertwingled in the same code block. He is also taking a gamble that the result of his selection

This only works if you can guarantee that the changes are not intertwingled in the same code block. He is also taking a gamble that the result of his selection will actually parse/compile/pass unit tests (select as appropriate) - he has no way to be sure of this. He is pretty much going to have to do a "get" into another working copy to be able to check this out, so I don't think he is gaining quite as much as he believes.