Mike,
My brother has been flying one of these with a DLE30 for approx. 8-9 years now. He flies it very hard with no structure type failures. He has thought about putting a DLE 20 on it however has not tried it yet. I believe he's using a 19 X 8 prop. The plane still slows down for nice gentle landings.
I just wanted to add some real experience to the conversation.
Jeff