I have a X32 and 2x S16. I noticed that some of the pins in the EtherCons of the AES50 ports might slip back (partially) into the connector housings. This ofcourse results in bad connections, sync problems etc. when moving the cables/connectors a bit. I solved this by moving the pins back in place (using a paperclip, gently!) and connecting the ports to Neutrik EtherCons that I put into my 19" racks. The Neutrik EtherCons seem much more reliable. Is Behringer aware of this (possible?) quality issue with the EtherCons? All of my units seem to have this issue with the EtherCons. So, I suspect that swapping them for new ones won't solve it, unless this was a batch issue which is already resolved.
If you want to check your ports: the 8 pins in the ethercons should line up nicely next to eachother. If one or more pins seem to be slipped to the back, you have the same issue.
Edit: Next to this issue I'm very very happy with the X32 and digisnakes (previous owner of SL24).