What is the point of having to wait less time if the match you’re waiting to enter isn’t a legitimate contest? Short queue times only benefit players queueing in premades, because they can farm more reputation and honor in a shorter period of time.
Waiting less time for a 0 honor game doesn’t help the pug.
If you’re correct about the ratio of premade teams, the system I proposed is likely to lengthen queue times for players who queue solo and shorten or leave unaffected the queue times of players queuing in with 7 or more members.
If Hph is your primary concern, queuing as a premade team will likely increase your Hph as a matter of course, as a result of faster queues, while also increasing the likelihood that the team you face will feature an appropriate composition and be better coordinated.
The only difference between the two systems is that the quality of gameplay is increased as a result of better matchmaking. Games will be more fair.