They did this in WoW and it worked great. Groups of 4 or more had to go I to the premade queue because premade offers significant advantages over pug.
I'm starting to notice on both faction sides of my server that there are pvp'ers you never see on your team. You only ever see them on the opposite (usually winning) team. This indicates to me that what the queue matching system tends to do is match the larger groups to fight a teams consisting of solos. You would think it would want to match with equal sized groups but that doesn't seem to be the case.
So the larger your group the chances of playing teams consisting of solo pvp'ers in increases. And I think the more experienced guilds have figured this out.
meaning: If two groups of four queue together it will be highly probable that 4 out of 5 of their matches will be against solos (let the pugstomping begin). Because the system doesn't try to MATCH a large group with large group, INSTEAD it fills solo players and groups of two around the largest group.
The rationale behind this came from solo pvp'ing over a span of two months.