Well, since no one answered my question I'll just post what I've done with the Italian Meringue Buttercream and how it holds up.
I made the buttercream with Kahlua so the base color was tan, but I was able to still get some good color into it. They're not as vibrant, but it still worked really well. I decorated cupcakes with it and so far they've been in the refrigerator overnight without any bleeding of colors, so they are holding up fairly well so far.
The cupcakes are for a party that my karate group is having for the end of the school year. I had to stick the cupcakes in a community refrigerator in the graduate lounge at school and I wasn't happy to find that the administration staff put leftover spicy wings in there. I'm currently worried about the transfer of smell to my cupcakes. Hopefully it won't be too bad.
Well I hope that this helps anyone else who is planning on using the Italian Meringue Buttercream. Thanks and you can see the cupcakes in my photos.