Some of us (Bill, Bhroam, Jon and myself) worked on capturing the use cases and the motivation behind those use cases that we thought were missing from the design page.
I have added the outcome of the discussion on the design page and it now mentions the use cases for multiple resource requests and node filtering as well.
Please have a look at it.
It seems the design proposal so far is in the right direction (for Use case 1 under conditional requests) where it allows users to submit jobs with multiple resource requests and also makes PBS scheduler select one of the resource requests according to how it has been prioritized (by admin or by user).
User case 2 probably needs something like "place=group=" to place the job on the nodes that have same resource value. But, since this can be requested in multiple resource requests, it needs to work in conjunction with use case 1.
Use case 3 however, can be addressed differently by providing a special way of packing the jobs on nodes where the nodes are selected in a way that they can be fully and equally occupied on the basis of cores the job has requested for.
For use cases related to filter nodes, a filter (as proposed in the design) provided with each resource request (that supports conditional operators) can be applied to address all the use cases.