Should we have NEEDS_CAPACITY/NEEDS_UPTIME behavior at all?
Does it make sense for us to have a set of relays that are not-Fast, and a set which are not-Stable, along with a set of circuits that can't use those relays?
Or would it make more sense to just say "all relays are suitable for circuits that need capacity and uptime; we don't list ones that aren't?"
I'm hoping we can come up with a quantitative answer saying whether we get a reasonable amount of use out of the relays that do not have these flags.