I run a small home based welding and fabrication shop and have tried just about every kind of bit you can think of. To be honest I have found very little difference in all the different coatings on bits. I own expensive bits to cheap Princess Auto/Harbor Freight bits and what makes a huge difference in the bits is how sharpe they are. I bought a Drill Doctor XP and give each bit a quick touch up and they cut much better. I would also recommend some stubby bits and a center drill as they have a lot less flex when starting your hole. Once you got a pilot hole I usually will move up by 1/8" to a 1/4" in drill size till I reach the finial size for the hole.