So I finally gave in to temptation and bought a new one from GC. I have read countless posts about the bad ass low end this mic delivers. So I connected my Allen Class Act II (gainy marshall territory) into my 2x12 with 2 V30s for some old school power chord crunching. The Allen delivers big time in the low end, almost too much when driven real hard with an LP and JB in the bridge. Anyway, I position the SM57 on one speaker angled and pointing at the area where the dust cap meets the cone, this position always works for me. Then I try the 421 at various positions on the other speaker and power chord away on the LP. When I play back the various tracks, the SM57 is consistently bigger in the low end, the 421 has more cut, regardless of where I position it on the speaker. So far, seems the sweet spot for the 421 is pointing directly into the speake cone, about halfway between the dust cap and speaker rim and about 2 inches back from the grille. Anyway, I don't believe for one moment that I have figured this beast out yet. Any comments and suggestions on using the 421? Does it have bigger low end compared to the SM57 when used properly? Really curious. Thanks.