Trigon inserts are pretty common in turning but not so much in milling. Why? I find them pretty lucrative, having six cutting edges, strong geometry and some manufacturers even offer ramping ability. The insert I'm currenly evaluating has maximum Ap of 7 millimeters, which is enough for roughing. Sure, everyone's favorite APKT inserts have more Ap and better ramping capability, but far worse cost per edge. What drawbacks are there?