The 9-spokers shown on the link are not the ones the U.S. smarts will get. Look for the 9s at various places on the smartUSA website; those have been verified by smartUSA. They are the ones with the outer ends of the nine spokes curving inward to a ridge about mid-width of the rim. There were different (smooother) 9-spoke rims provided on 450s which I like a bit better than those that we are to get.
Between the 9s and 6s, I prefer the 9s. Actually, I like the 12s the best.
I suppose it depends on which 6 (or even 5 spokes) might be available. There are some chromies in the euro cataloge that look nice, although as someone else pointed out, I believe the rear brakes are drums, so while the open look (5 or 6 spokes) looks good on the front wheels, they might not look as nice on the rear. SO I'm with you....I think I like the 12's vs the 9's better.