What you got now is what a lot of folks do. They may sub an Audix I5 or a Beta57 for the SM(not a huge difference there). The new Sennheiser evolution snare mic is killer by all reports(but I have not had it to try yet). Underneath can be most any SDC and some just use another 57. The Granelli Audio
http://www.sweetwater.com/store/deta...FQK8sgodFDdGDg might solve your placement problems. Sometimes the SDC can get taped on top of the 57(both mics up top to avoid phase issues). Any time you use a bottom mic, phase/polarity reversing one should be done(your choice on which so try it both ways).