I'd like to throw my vote in for this also. Having had the slicer for just a week now, that is really the only thing that I feel like I am missing at this point.
As of version 3.0, you can now divert travel paths to avoid crossing perimeter outlines. This option is on the Advanced tab. There is even a setting to allow setting the maximum detour factor (i.e. only allow detours that are up to 3x as long as the original move)