I definitely don't hate the idea, but you might be creating more work and potential problems for yourself with a rack system. if you have the capability and hardware to wire each individual shelf by yourself (which I certainly don't), why not take the time and build stacking cages or something with more versatility than a rack? for me, rack systems are purely a function of convenience. if I had the money, space, and wherewithal to put in lighted display cages, I'd do it for every animal I own. also, I think the expense of wiring each individual shelf to run on its own regulator would be more costly in the long run than buying multiple racks that have less capacity for each different species. that way you only have a few thermostats and more money to spend on caging, plus less worry about electrical shorts or tweaking temperatures. likely a cheaper electrical bill as well.