Ive had a look at one and taken it apart - I was under the impression that on the hugget the shroud dosn't really do anything extra but look pritty, there is no way for the air to get from the silencer or the barrel back down the shroud and out the nice vents at the bottom (from what I saw) they also are machined in a way once you have the shroud fitted you cant fit another silencer.
My personal opinion is - the silencer itself is very good (par with the HW), the silencer and shroud combo dosnt give enough for the money, however they do look very smart.
Perhaps you should speak to Risi