Well, I'm squarely in the "buy a milspec 7075-T6 alloy lower" camp though I know many people like to try out polymer lowers. But I just don't see the advantage of polymer. Weight or price (since if you catch a sale there are $50-75 milspec stripped lowers.) Also no one has been able to prove their polymer lower is stronger than 7075-T6 alloy. Comments are welcome... Of course many vendors and polymer fans claim the polymer lower will save you a pound of weight or 1/2 pound but when you compare the weight of stripped lowers there isn't much difference. (Larger differences tend to be complete lowers somehow fudged toward a big polymer weight savings. Heavier stock, heavier buffer, BAD lever, etc. added to the alloy lower.) Approximate stripped lower weights: 8.5 oz ... Milspec 7075-T6 alloy 8.0 oz ... ATI Omni hybrid (fiberglass with zinc inserts) 6.8 oz ... Amalgamated Ti titanium 5.9 oz ... Mag Tactical (proprietary alloy) 5.5 oz ... Generic magnesium alloy 4.5 oz ... Bushmaster Carbon-15 4.5 oz ... New Frontier LW-15 For a 4 ounce or less savings toward the rear of the rifle where there's little impact I just can't see taking a chance on polymer, maybe there are good ones but for hard use I don't trust their durability.