Assuming you built your
RMH out of an appropriate refractory material, then yes, you can burn any wood you want. It
should be designed for much higher temperatures than the woodstoves that you might heard of being harmed by burning hedge. There's no wood that's off-limits. (I figure the wood you're talking about is hedgeapple, right? Bodark? Bois d'arc? Horse apple? Osage orange?)