Slide vs (Dup loop and slide) ...

[VladD]

Bevel isn't the way to go indeed.
Right now, on a partial loop, the closest way (both in modeling workflow and, probably, in erlang code) in Wings3D to get this "loop offset" (as maya calls this very function, as suggested in the first post), is to do an edge extrusion and just changing the % value of the added parallel edges without adjusting the D(istance) of course. Then a bit of cleanup on the partial loops ends. A bevel would imply more cleanup, without the benefit of keeping the original, "central" loop. So, an offset/duplicate loops command would just be like an edge extrusion command without the Distance input, basically.

btw, I second FB and PP suggestion for a "pinch" option in the slid command, to either get closer together OR conversely slide appart multiple loops, that would be a nice addition too.