I'm definitely weary of handing over my DNS data to a company I don't know. Besides, Safari ad blocking plugins already take care of this while surfing.
This may have unintended (both good or bad) affects on normal app experience since it's configured on the network.
For a few bucks more a month, I'll sell you a proxy service through which you can proxy your DNS requests to optimal!
We are not selling this information and never will. We built a safari blocker called fewerads that's in the App Store. But we found lots of users wanted to block ads in chrome mobile or inside Twitter or Facebook (to be clear, web ads, not those platforms' ads), which is what lead us to this idea.