Yeah, the SMS is quite simple, but the Behringer BFD is cheaper and I think it does a better job.
You are right, there is a bit more of a learning curve with the BFD, but that's what makes the hobby fun.
REW used with a BFD allows you to change something in the room or change a filter and then do a response check and overlay with another (up to 8) responses to compare.
brucek