In the past I used a 2 1/8" self-feed for 1 1/2" ABS, now that I have a set of Blue Boar TCT's carbide hole saw bits that is no longer the case. These things cut through studs like butter and I can stay cordless without having to pull out that heavy ass Hole Hawg. I will probably stay with self-feeds and augers below 1 1/2 but anything larger and it is carbide hole saws for me. You guys the same? or sticking with the self-feeds?