^ I don't see him simply draining the rings of their power for an easy win. He never simply drained the classic Quantum Bands or Mjolnir or the Novaforce or non-insane Genis-Vell's Nega Bands, etc. Of course... those aren't perfect analogies. Classic Quantum Bands and Nega Bands had instant access to the unlimited energies present in the Quantum Zone and their rings have limited charges. Mjolnir is magic. Novaforce is imbued within Nova and not in a weapon... But I think it's too simplistic to suggest that Surfer wins this because he simply drains the rings of power.
But Surfer still takes this fight for the other reasons you stated. Hal and Sinestro are not in his league. They are decently analagous characters at best. Multiplying them by two doesn't change things.
was just looking at a scan where Surfer drained Hulk back down to Banner, whilst blocking a punch from Hulk.
also, in one of the cross-overs, Surfer has shown the ability to contain all the Oan energies in the central battery...
as for the lack of drainage with other characters, it's quite simple imo, he just never thinks it necessary. he's taken the Power Cosmic from other Heralds, because he deems them troublesome enough (Dominas for instance), he can clearly manipulate Odinforce, in effect bestowing it upon BRB so that's one that I think is arguably there to be absorbed/drained.
the Q Bands, I think they're supposed to be the inverse of the power cosmic, so perhaps he can't effect them but it has been stated that Galactus can absorb the negative zone so perhaps ...