I have the flip view case and it's not a problem. There really isn't a sharp edge on the flip cover, and the cover is also ever so slightly shorter than the case part holding the phone.
What I have happen though, my pinky finger is usually on bottom "supporting" the whole thing. With the flip view open, it nudges my finger over to where it covers the mic. Took a while to figure that out, I just needed to retrain myself to move my finger to the side in more of a grabbing grip.