My Oryx's work fine as long as they're well adjusted. With kool stop pads I can easily lock the wheels up, even on realy steep downhills. I don't have any expeience with really powerful cantis like Pauls, though I imagine they are certainly better, they probably aren't 6 times better, even though they cost 6 times as much.
Whatever you get, I'd get something with V-brake style pads instead of old school cantis. I have both kinds and with the v pads the brakes are way easier to adjust. Kool stop pads help too.
If it were me I'd only shell out for the Pauls if I either had a ton of cash lying around or if I were screaming down some extremely steep singletrack descents (at that point though I might just want to get disc brakes).