I would love to do a wedding cake with IMBC and using a stencil but not sure how the IMBC will stand up or how long can it stay out of the refrigerator. As you know wedding cakes can be left out on display for hours before they start cutting/eating.
AIt depends on what climate you have really. IMBC and SMBC don't cope well in heat. If you leave a stick of butter out and test how firm/soft it is, that is how firm/soft your IMBC/SMBC will be. As for leaving it out of the refrigerator, it won't spoil in a day. I've left it out for 3 days and it has still been yummy! I used to love IMBC as I found it easier (you don't have to baby it like SMBC) but I actually prefer SMBC now. I bought a massive stainless steel bowl from ikea so can make huge batches and I like the fact that you can heat it up to the exact temperature that eggs are cooked at so you know all bugs have been killed. I know pasteurised eggs are heat treated to kill all bugs but we don't have pasteurised eggs in the UK... That I'm aware of.