That worked for me three or four years ago, though I looked at CTR, not eCPM. Not sure I'd get the same affect today.

It's hard to say because we are in the dark regarding smart pricing information, but I removed ads from a gallery on a site when my EPC gradually declined overtime and 1 year later the EPC is fortunately back to the original level. I don't know if it's related, and I may be losing money because I'm not putting ads in that section anymore, but as long as we have no information with smart pricing, we have to shoot in the dark and pray.

So 100% of your 2 opinions "may" be a yes.

Here's my suggestion:

If your eCPM is so low, why not remove AdSense and experiment with other forms of advertising? You won't lose much and could end up finding a good match. I tried that and found, after some time, some ads that performed so well that 2% of my pages were producing 20% of my income.

Before removing AdSense these same pages were bringing in pennies at best. Now I'm wondering what would happen if I put the same ads on more than the poorest performing pages.

Couldn't tell you for sure about this being a cure for smart pricing. I haven't really lost any sleep over smart pricing in a long, long time.

why not remove AdSense and experiment with other forms of advertising

Because I did already with horrible results.

I don't loose anything experimenting the low ecpm removal, but since I'm having a big drop and no certain causes don't want' to confuse more.

Anyway a possible step would be identifying 10 pages with channels and low performance, notice the domain adsense income in last week. Then remove ads from those 10 pages, and 1 week later check domain savings that week. If it gets better, low ecpm *may* be the cause. If not, well I don't know.

Should I try with lowest ecpm or lowest CTR? (or both?)