Or "Slice n Splice". Would definitely be cool to have, with the option to keep the original start point (or not).
I often cut down loops to minimal fractions and multiply them back long again, but then by using combinations of Instat Divide and Instant Multiply to hit the duration values I have in mind. It's different from the processing Philip brought up in this discussion. (talking Mobius here, in case someone reading this should wonder)