Has anyone had success stenciling on chilled smbc?  Does it have to be a crusting bc? 

i have used a stencil on smbc with an air brush -- had to hold the stencil just away from the surface and sometimes i overpiped the design afterwards so while it was a stencil it wasn't like how you do it on regular crusting bc -- where you slap it on the surface and apply paint or royal and remove the stencil voila 

I have not done so on SMBC, but I have done it with my regular non crusting buttercream.  I chilled the cake until the buttercream was firm, and then stenciled with a colored buttercream over it.  I found that Idid have to return the cake to the fridge to keep it hard, and make sure that I was gentle in holding the stencil to the cake. I used a small spatula to thinly spread on the buttercream over the stencil, then removed it.  My biggest issue was not returning it to the fridge to keep it hard enough to stencil on as I went along, as I got caught up in the stenciling.  Since SMBC is a heavy buttercream, you should be able to firm it up good in the fridge to allow for good stenciling. HTH. :)