I tried making this buttercream but didn't have much success with this recipe. I doubled the recipe and used the butterfly, but ended up whipping the butter in my Sunbeam mixmaster as it wasn't whipping enough, and then transferring it back into my Thermochef to finish the recipe. I found it hard to dissolve the sugar without it overheating and melting the butter.
On the plus side, the buttercream tasted nice and didn't crust over. On the minus side, I had trouble with the icing tubes blocking - probably because the sugar hadn't dissolved properly. I had some icing left over, and decided to make some more flowers the following day. I did what I would normally do, and beat the icing with a pallete knife. This resulted in a lumpy mess as the water molecules disintegrated.
I did have fun piping the buttercream flowers, especially after I made a batch of buttercream using this recipe
http://gastromony.com/wiltons-buttercream-icing/