I use all (down/up/compression) depending on the situation, similar results. I can get a cleaner cut if doing a clean up pass, but cutting twice is no fun; and still not close to off the saw quality. I have slow bits, but the added expense and shorter life are steering me away, I use them mostly for plastics. I've been using whiteside mostly except for the slow and some other fancy bits from vortex; but I nevered compared the same style bit from the two companies. I know vortex is pretty highly regarded, so is whiteside - at least for standard router bits, now I wondering if the spirals, since cheaper, maybe not up to other manufactures quality.
The reason I was thinking carbide tipped because dados and the router table with carbide tipped, rabbets too, and cleaning edges on the jointer all yield the results I'm looking for, close to saw cut quality. I was thinking since my machine isn't cutting super fast and super rigid I'm not taking full advantage of the spiral design. I've seen down, up, and compression style carbide tipped bits - seems like the slicing action you describe of the spirals would be somewhat present in the bits of these designs to maybe that might be something to try....guess I have a lot of test cutting in my future.