DXM2 will only hook to one frequency whereas DXMX will look at every one of them that is available, and connect to at least two signals just in case one fails. That being said, my DX6i was DXM2 and I never had an issue. If you are flying where there is a lot of signal traffic, then get the DXMx, otherwise just get the DXM2. Just make sure it's not one of the first ones to come out that had a recall issue. Those will cause your plane to crash since the sticks stop responding because the pots are bad. Hope this helps.