OK. I have a wedding cake... 2 tier, covered in fondant. all this client wants is som scroll work and beaded border. i'm debating if I should do the scrolls in royal icing of buttercream? is there an advantage working with the royal icing????

I think butter cream tastes better.....thats my only contribution I can give

I agree that BC tastes better and has a better texture. I think the RI is just more durable. Not sure though and have wondered this same thing so I'm looking forward to some more experienced input on this topic.

RI seems to stick to fondant better than BC, at least it has for me.

RI sticks better to fondant for me and it also seems to not break as easy when piping and doesn't show any airbubbles. It is also easier, after it dries, to gently pick my mistakes off the cake. (I've made more than enough mistakes so I've got that technique down really good)!

I use BC for everything.

There's no clear advantage to either. It's by personal perference only so you just have to get experienced with each one to make that determination. I too would use buttercream for the palate factor.