I use E604s and MD504s on toms instead of SM57s.

• An E604/MD504 can take an unlimited number of direct hits. An SM57 is much easier to damage.
• E604/MD504s have a more consistent sound than SM57s. The variance between the sound of individual SM57s is much higher.
• I prefer the proximity effect of the E604/MD504 more than that of the SM57. Mic'ed with an E604/MD504 very close to the edge of the head, a tom sounds more like a tom.
• If the drummer has a tight kit, an E604/MD504 will be easier to place than an SM57.

But... the clip that comes with the E604/MD504 is less than ideal. Sometimes it works, sometimes it doesn't. You don't get much of range in terms of positioning. Most of the time, the mic ends up being too close to the center of the drum head. (The clips do work well with drums that are ring-suspended... you can attach the clip to the ring.)

If you've got a crucial gig, bring a set of regular mic stands to use with the E604s just in case.