Skill dilution happens with this many medics on a scene, even if you don't see it that way. At any given time, only one person can run a scene, only one person can pass a tube, and only one person is truly making the patient care decisions. I won't say too much on this, but I'm completely with Bullet regarding his thoughts about running fire apparatus on medical calls. These are highly specialized vehicles, and even with a few bags of medical supplies tossed in remain wholly unnecessary on the vast majority of EMS calls. I really am glad this model works out where you are, but it's a complete disaster in most of the country.
First I will say that I don't work in Craig's system, although I do have a lot of experience working with several providers from his department. Then I will say that I do work in a rural fire based EMS system.
Now, about the skill dilution:
I believe that in a system like Craig's, the intense oversight and pressure to perform highly keeps everyone performing with the precision that is needed. From my outside look at the system, the laissez faire freedom of the medic in the ambulance doesn't exist. There is no cowboy time- everyone is always in the presence of 1-2 experienced medics on scenes, which leads to more compliance with what can be seen as the standard of excellence.
Compared with my rural fire-based EMS system in which the only time I see another medic is in a meeting or at the hospital, I'm totally on my own with limited feedback and no help.
You tell me whether you want skill dilution or wild Wild West.
I think somewhere in the middle is a budget-possible medium. Our system literally can't afford another medic, whereas theirs is swimming in them.
Locality funded EMS is always going to have some drawbacks in that arena.
I do know for sure, that in a similar situation as that asthmatic arrest Craig tells about, the patient would have died. Even though I consider myself to be a decent medic, there's no way I could get the work of 5 experienced medics done in time to catch that little girl before death ran off with her.
This is a function of system design, funding and leadership structure, but it also illustrates that in a system with extremely limited resources, having a medic on the engine only costs 10-15% more and can result in dramatically improved outcomes in critical cases.