I've worked for several publishers (500k-5M UVs - comScore) and deal with this recurring problem:
Do you use iFrame and block all expandable creative? Has this impacted revenue?
Are all of you using a workaround customized for your site needs? If so what ad servers are you using?
If you're not having this problem or have overcome it easily, what ad servers are you using?
Thanks in advance for your input.