I have a customer who does not like buttercream icing. Is there a whipped cream icicng heavy enough to decorate with?

Wilton makes a wonderful boxed whipped cream icing that is great for decorating - stiff enough to make roses. It's a powder that you add a cup of ice cold water to and it makes about 2 cups of icing.

http://www.wilton.com/store/site/product.cfm?id=3E311491-475A-BAC0-58E4AB9291C5910C&fid=C763B248-475A-BAC0-50AAF0C8507DBEB2

I must admit that I do not like most buttercream frostings... I love whipped cream frostings though, but I have heard that you can't really decorate with them because they are too soft and/or won't hold up well for an extended period of time. My first MIL makes pretty good buttercream though, so I guess there are different ways to make it. I do have a question though... is there much of a taste difference between just regular ol' buttercream and IMBC/SMBC?