I had a look at the latest version of draft-ietf-ippm-qoo. 
I think that the document is Ready. 
From an OPSDIR point of view, it is good to have Section 8 on Operational Considerations. 

I would add some considerations about the sampling frequency and if it has impacts on the network performance. 
An additional question is related to Section 9 and if the authors have considered other techniques defined in IPPM to help to solve some of the pain points mentioned in Section 9.