Hi, Kim. Welcome to DC. I'm sure you'll receive plenty of answers to your question. However, I'm with Tatt. You will lose the "buttery," sorry I had to use that term, texture that buttercreme is all about, as well as the flavor.
Can you tell us why you want to make this substitution?
"As a girl I had zero interest in the stove." - Julia Child
This is real inspiration. Look what Julia became!