I have freelanced with crowdsourced testing companies for two years and have learned a lot about the processes, platform tools, freelance tester communities, product management, challenges, and shortcomings from the tester side. In the last year I have expanded my knowledge by running a high volume of testing with crowdsourced testing vendors for Android, iOS and mobile web apps at my current company as a customer. Overall it has been very successful based on the feedback and data that we received from freelance testers. But it hasn't been a bed of roses as it has taken some trial and error as a customer to obtain the right knowledge and experience that in turn helped accomplish our testing goals. I highly recommend that your in-house professional testers handle the relationship with the crowdsourcing company(ies) because they understand your testing needs and your company's business.