Now that there exists a Rollup issue for SystemJS, we'll need to be able to hoist function declarations, while retaining SourceMaps.
I haven't been able to find any move method, and the method combination that could have replicated the behavior (snip, remove and insert) requires insert to work on MagicStrings in addition to strings.
I suggest extending MagicStrings API with either a move method, or an insert that supports MagicStrings.