I know there are many variables in this question, but in general do Mobile Pops convert better then Desktop Pops?
Also, in general do Mobile Pops cost Less then Desktop Pops?
Assume it's the same offer/same lander/same network. (as much as possible)
I've seen a big push to go for Mobile Pops these days and was wondering how different they really are.
From my experience:
1. Does mobile convert better than desktop? Yes, CTRs and CRs are usually higher but it depends on the offers. Short offers like leads, apps, etc tend to convert easily on mobile but long form offers or payments are more difficult to convert.
2. No, on average I've always seen desktop pops are less expensive than mobile, with maybe a few exceptions in some countries.
Lots of people pushed mobile for the last years because mobile was kind of new against desktop, but it¡s good to test both if the offer allows it and get data for yourself.
It also depends on the vertical ... for example in adult dating, desktop generally converts better than mobile, even the payouts for mobile leads are smaller and mobile traffic is less costly.
As usually, there is not an easy answer to this question 
If we talk about SweepsTakes, I can say that WEB traffic on POPs can converts not worse than MOB, in some cases even better. If you look at the inventory in any POP source, you will see that there are a lot of cheap WEB traffic, which you can buy, for example, with $0.2 CPM.
Even if CR will be lower than with MOB, don't forget that you can pay 5-10 times less! So there are a balance.
By The Way, I will post an article about WEB POPs soon 