's up to you, but those headset bearings don't look so bad in your photos. Inspect the balls and races with a magnifying glass and strong light. If you can't see definite pits and rust on the balls, then I'd reinstall them. The thing to watch out for on the races (the inner and outer "ring" parts that the balls make contact with) is "brinnelling," esp. on the bottom (fork crown) race. That's where the pounding of road violence, coupled with the tendency of the balls to remain in pretty much the same position for long periods, makes dents in the races -- and flattens the balls too. Brinnelling = partial or complete headset replacement. It's what causes old, worn-out headsets to have that "ratchety" feel when they're turned. You want to keep your headset analog, not digital or quantum, in its turning ability. The other useful test for races (applies more to bearings that turn constantly, like hubs) is the "ballpoint pen" test -- clean up the race in question, and then run a Bic-type ballpoint having a small, metal ball over it, along the same path that the bearing balls take (that is, circumferentially). If you feel roughness, then the race is overworn.

I know that lots of folk have a penchant for loose balls, but I can tell you that when it comes time to disassemble, caged balls are heaps easier to "manage." It's a lot easier to pick up the cage off the floor, than to be trying to beat the cats to all the balls that have scattered; and headset balls really like the cracks in wood flooring!