My personal opinion on this is frankly I do not see an issue with mixing Allocation models in the same provider, AS LONG AS, the provider vDC was mapped to the cluster level. I would retract my statement if you initially created RP's in the cluster, then created Provider vDC's to those, and THEN created org vDC's. That is where you will run into sibling rivalry issues. However if a Provider is Mapped to a cluster than ALL org vDC's will be top level RP's in the cluster and there is less of a chance of rivalry.
That being said there is no issue with having different org vDC's as PAYG with different settings. That is the whole point really where I see your three examples as Low/Medium/High, but being PAYG they can be sold as that. The time to use Allocation/Reservation pool is for an organization that wants their resources Gaurenteed. Again, you can have that Org vDC sitting on GOLD along side the HIGH PAYG. There is a case to be made that LOW PAYG on a GOLD pVDC just does not make much sense. At one point I had a matrix of Gold/Silver/Bronze and LOW/MED/HIGH PAYG and you could see that certain combinations just did not compute.
----------------------------------------------
Chris Colotti
http://www.chriscolotti.us