I was just being a jerk. I don't think there is any reason why you should worry about the amount of flex you can get in the s300's unless you are doing standing starts at a track where power really is an issue. In the case of going up hills flex in the crankarms shouldn't matter at all. The only think to worry about is metal fatigue which really shouldn't happen with the s300's, though someone just had a picture of broken andels. The more pressing concern is tacoing the chainring, which has more to do with making sure the bolts are tight enough than anything else.