Is there any difference in the brands of weights? I know some say they are balenced within .1 gram of each other and are alot more expensive. Is there really any difference

Profile can be different, also center of mass might be in a different spot. Not sure what brands your looking at but balanced to .1 wouldn't make me spend a whole lot more money.

the polaris 10 series and comet A series are both nearly identical profiles but the width and where the bulk of the weight lies are different,which changes their performance totally,.1of a gram difference is pretty close tolerance,when you buy comet arms they used to guarantee their weights to be within +- 1 gram