Check out https://www.growandconvert.com/ by @benjihyam and Devesh. They primarily focus on conversion and content marketing ROI. They have very extensive posts, case studies and no high-level crap. Real-concrete stuff
Also, I love mobilegrowth.org, a community by @amandale. She hosts excellent AMAs with mobile experts from Yummly, 8tracks and more, plus discussions open to all members to ask/join in.