Using smaller rectangles to get CPM advantage?

Even though larger ones work better....

[JohnKelly]

Since most of my ads are using older AdSense codes (without the "google_ad_type" line), I'm thinking of updating the code to contain google_ad_type = "text_image". This would appear to then allow me to display ads on a CPM basis, which would outperform CPC type campaigns if the AdSense instructions are correct.

However, not all ad formats allow images. For example, I'm now using 336x280 large rectangle format, which only allows text ads. The next closest size that allows both text and images is 300x250 medium rectangle. but previous testing shows the large rectangle works better.

So, any advice here?

[ShunT]

From the feedback I've bee seeing, site-targeted CPM ads aren't doing as well as they're thought to be (atlest from a publisher's perspective). Try it on a few channels and see if it out preforms your CPC ads...