Is it true that AdMob gives low CPM for developers who combines...??

Is it true that AdMob gives low CPM for developers who combines more than 1 ad network that is not available in their mediation list ?
Example,
Admob + StartApp
or
AdMob+ AppNext.

&
Will i get banned from AdMob if i use their interstitial without their invitation email ?

Not sure about your first question.

I have been using their interstitials since they upgraded to the new Admob without a problem and no invitation e-mail.
Its my understanding that you do not need an invitation e-mail if you’re using the new Admob.

Hello,
I don’t know if i am using new admob or not.
I have attached a screenshot.Please tell me, is it new or old ?
admob.jpg
How can i switch to new AdMob ?

Thanks.

That’s the old Admob.
When they released the upgrade you got an e-mail and a notice at the top of the dashboard when using Admob.
It still isn’t available in certain countries as far as I know. I might be wrong though.

Maybe someone else can shed some light on it.

Its not available in places like india and some other countries, i have old admob , yet Im having no issues using it. About the ecpm, ive been using it with startapp since day 1 and they were varying from 2-4$ ecpm.