I will be icing with buttercream, and would like to get your opinions if I should use royal or buttercream for the scrollwork. I tend to think buttercream, but just not sure. Any help appreciated.

I think I would DEFINITLY go with Buttercream. If you are icing your cake with Buttercream, and then do ROyal icing on top, the grease in the BC will break down the Royal Icing.

Ohhh, good point. I just didn't know if it would look cleaner or stay on better, but will go with buttercream. Thanks!

I'd use buttercream, but not for the reason above.

Yes, grease-free utensils while you're making it, but it doesn't have to be a grease-free surface that you pipe it directly onto, nor completely dried to stop it from breaking down. (moisture is the culprit.)

There's a similar thread from a few days ago that discusses what causes royal icing to break down titled "Deciding between fondant, icing, gumpaste, and buttercream". I'll paste what I wrote below...
Here's the entire thread: http://cakecentral.com/cake-de.....html+icing

...you can apparently make royal and pipe it directly onto Crisco greased forms and pipe into cooking-sprayed foil-lined lily nails!)

If you'd like to read what others have experienced, TexasSugar says that it's caused by moisture in this thread "question about royal icing":
http://cakecentral.com/cake-de.....html+icing

and here "Royal icing decorations":
http://cakecentral.com/cake-de.....html+icing

my favorite "will piping gel break down royal icing":
http://cakecentral.com/cake-de.....html+icing

another favorite, "Royal Icing Lilies, Cooking Spray...":
http://cakecentral.com/cake-de.....html+icing

Also, have you ever seen those "Happy Birthday" RI letters in the packages at the grocery store? They are made to go on cakes with icing.

Normally, I use buttercream for scrolls unless the client wants the scrolls to be silver. At that I point, I use royal icing on buttercream cake with no problems.