I use the marshmellow rolled buttercream recipe too. It's a sort of hybrid. I did find the RBC was greasy & stuck to the bags when I packaged my sugar cookies. I did like the taste. But the hybrid is really good too.
I got impatient with royal. My piping skills aren't super fab. And, I've run into another problem with drying time and royal. I did post a question that nobody could help me with. But...oh well, looks like I'll be making little boxes for my cookies to rest in before I bag!
Oh - rolled icings are great because they are super neat. You don't have to practice a bunch to get it right. I like to imprint mine lately. I recently bought a clearance item for the cuddlebug & used it for imprinting. It was only $1.
I also half the recipe. I think it calls for 10 oz of marshmellows. I cut it in half with no problem.