I'm somewhat of a newbie, and I'm considering getting either the mxt115 or mxt275 and I can see the advantage that the 275 has with the integrated controls on the handset. Why would anyone choose the 115? It costs the same and has pretty much the same specs except that all the controls are on the base unit. Am I missing something? Can anyone who's had experience with both, tell me what advantage that the 115 has over the 275?