I thought the Infinity's were just a bit bright. I didn't think of the JBL 530 as bright but slightly forward sounding. Both are good budget speakers that play well in the $400-$500 range imo. They aren't giant killers, like one might assume from reading online, but they are a great value.So even the JBL's are a little bright, but people say the Infinity's are brighter? Hmm. I think Harmon has a month return policy so if you want to try them you have that option. They're fairly big to pack and move though. I couldn't advise you whether the 263s or 253s are the way to go. I got the 263's on sale but they were still, I dont remember, $50 more than the 253's per speaker.
One thing everyone seemed to agree on is that the Infinity RC263 is the best center channel in the price range, and better than the JBL center. Some even used it with JBL towers rather than use the JBL center.