Well as you can tell by my username, I truly believe CPV is one of the more popular ad formats in the past few years. I've been running popunders on my site that gets over 2 million impressions daily and I had many success with it. The reason why I believe CPV works well because visitors does not have to make an effort to do anything with the ad. As long as the ad successfully loads, you earn money! Of course it's easier said than done, but from a webmaster perspective, it's great as long as the ad loads quick and is not related to any malware issues.
The problem people have with CPV is that it slows down their website and afraid that visitors get annoyed with these pop ads. My advice to you is: stop setting your frequency so high! The higher your pop frequency is, the more ads that will show up, hence that will annoy the heck out of your visitors. People have the mentality that: more pops at once means more profit. That is wrong! You need good quality traffic coming in to convert those visitors into cash; simple as that.
I worked with quite a bit of ad networks such as PopAds and AdOn Network which I had success with, but my latest experiment is with InfinityAds (fairly new site I think, but found them on Google Search). What really sold me in testing them out is their five dollar payout which is insanely low so there was no risk at all. PM me if you want to take a look at a report taken from my account to show the success I have so far (as I can't post links yet). Only problem with them is the consistency of their ads, so I highly don't suggest you to try it if you only get 1,000 impressions as you will earn next to nothing.
Hope this helps for people thinking of going into CPV, it's really something to consider if you want to make big bucks in the online world.