I had used Google Opinion once when I was in college. It is one of best and least known products of Google. Allowing people to view surveys based on their location will help gather data in a much precise and acute manner.

 

Don't know about the lower payout per survey (seems like it's been about the same).

However, I am late to any tips/tricks for this app. I've been using it blindly for over a year or so and I just synced the survey in Settings and I've been getting alot of surveys in the past week.