Regarding CPU-intensive QA tests (builds and piuparts runs): I think
that it's very important to do them on mentors.
Might be helping the sponsor to determine if the package builds. But I'm
not sure if it's worth it. Just my personal opinion.
I don't think that resources are a problem: nobody said that you _had_
to host mentors yourself.
It is a rented virtual root server with enough power and 1 TB of free
traffic that I pay for from my spare money. I think it would be able to
do that if needed.
I might get you wrong but to me you sound more like "If you are
incapable of running the service properly then let someone else step up"
instead of "I think that test builds are important. If you agree but
don't have the proper resources I can perhaps offer some computing
power.". Sorry if my emotion chip got you wrong.