Lately I have gotten lots of indies asking me how changing from paid model to free to play has worked for me. Answer is: smashing success.
SuperDD has been downloaded over 900k times by now. Duke Dashington and Tiny Dangerous Dungeons were paid apps, and didn't get even 20k downloads combined.
Of these 900k players, only 1.91k has bought the Remove Ads IAP. But that doesn't really matter, as the ads are the main thing here. With the ad revenue, I could easily quit my job and live comfortably for couple of years as full time indie if I wanted to.
The sad fact is, there simply isn't enough paying customers on mobile for unknown little indies. With a free game, people have less threshold to download it, and people who don't want to or can't pay can still play it. If you can also nab App Store feature with it, your game spreads like wildfire.
Paid games might have more success on PC and consoles, but for mobile, I'm sticking with free+ads model from now on.