I think the impulses are awesome, definitely better in a more full mix than out of context. They get rid of the honky midrange while keeping low and high definition. I don't think they stand very well if you only use one impulse, so just using the 57 alone sounds too thin, just using the 421 doesn't have enough hi end definition and clarity. I'm not sure about the other mics because I haven't experimented with them much, but I'm sure the same applies. Matching two or three cabs and blending them makes all the difference. I also personally prefer a the 2x12 cabs over 4x12, but that applies to live guitar playing also in my opinion.