From the very beginning of using Adsense I have always created a single ad unit and a custom channel to track that ad unit. So for my index page I would have:

Ad Name: Home Page Top Left
Ad Channel: Home Page Top Left

Ad Name: Home Page Bottom Left
Ad Channel: Home Page Bottom Left

My question is, now that they have responsive, I dont need different ad units since I can use CSS to define the size for each ad placement. However I still want to be able to determine what ads are getting what clicks. Is that possible? Could I just create a single responsive ad to use for one site and then create different channels and assign that channel to each ad?

Ad Name: Global Site Ad
Ad Channel: Home Page Top Left
Ad Channel: Home Page Bottom Left

Will reporting allow me to run reports to track which position is getting the clicks? I just find it tedious to create ads for each slot.