How beneficial would it be to link these two accounts? Some of my sites have a low CTR and impressions so would this hurt my ads? Any help is greatly appreciated.
analytics will do nothing to your ads you can just keep track of pages that generate clicks it is like detailed reports for adsense earnings
The new AdSense interface is coming soon which is going to show same or more details we see with Analytics link up. It's better you interlink both account. Only beneficial for details, don't expect effect on earnings.
it is beneficial in terms of tracking statistics for me. If you are familiar with Google Analytics you can see you Ad Sense earnings there as well. I don't think that the analytics has something to do with earnings from you ads.
Does anyone know how often google analytics updates? I also often see differences in visitor counts between the two
For me it updates approximately hourly. Analytics allows you to apply filters. If you created any filters that could explain the differences. I also assume that Google have different storages for both AdSense and Analytics statistic. They may differ during the day but at the end they should be close as numbers.