Decks, Patios, Porches and Docks - Longevity of railing spindles vs material

Looking for advise regarding longevity of painted railing spindles. Two material choices, CCA treated pine or untreated hemlock. Either would be primed with oil base and topped with exterior latex. For the past ten years painted hemlock spindles have performed satisfactory on our coverd sun exponsed porch. We would like to use the same spindle (turned profile) on our exposed and shaded deck but are uncertain about life if not CCA treated. Is CCA treatment necessary to prevent decay if painted? Obviously when paint fails CCA treated will last longer. Will paint perform better on treated pine or hemlock?

knussml,
If you can find the exact baluster profile you desire in the PT lumber I would still go with it. Even properly treated the hemlock verticals will last quite awhile. The horizontal rails should probably be PT also, since these will collect some standing water. Before you prime PT make sure they are dry enough, and I would paint both the top and bottom for a good seal prior to installation. It's the moisture in the wood, or absorbed by the wood, that will cause paint failure. I just read an outdoor painted project article in WOOD magazine and they suggested exterior OIL over the oil primer.
good luck,
fred