You could use some shrink wrap around the connector body and onto the wires to provide some strain relief for disconnection grip. I've also seen people use shoe goo or similar glues to build up a strain relief at the back of the connector body to give them something to grip for disconnection.
Lastly, if you find that you've got poor solder connections on the deans, then I'd work on the soldering skills before using or changing things to EC3. I find the EC3 pin cups a bit more difficult to solder cleanly (without overflowing the cup and ruining the pin) and it can be more difficult to see the solder joint than on deans connectors where everything is exposed. Deans also allow desolder and resolder without much hassle, compared to the ECx pin cups. Especially if you've already put the ECx pins into the connector housing.