The jet that comes from this should be a dark red it would fit the theme more than the standard melta beam. Not really a high priority but since it glows red it would fit it thematically as it would look like it's spitting pure hellish rage at the target.
Well, visual effect for these weapons is not done yet. Like how the RTS PC shoots blue balls instead of orange.
It is probably lower on the list of priorities right now but hopefully they will add it in for launch.