Probably plenty of watts. My concern would be the current drive with the 4 Ohm load of the MMGs.In one system, I run an Omegastar 170 (granted, the Dyna heat sinks are smaller than those in the 240 EX) and it gets pretty hot if I use 4 Ohm speakers. I'm not sure what the MMG's impedence curve dips to. Why don't you ask Frank? Don't know if he would steer you to the 260 EX, or not, but you will get an honest answer and his best advice.
Tom