How robust are SMD DC power inlets compared to through-hole?
The answer to your question depends a lot on how the SMT connector is applied.

The SMT connector can be rather robust if you have large copper areas that surround the mounting pads. If you just place small pads that are just barely bigger than the SMT leads then it will be much easier to rip the connector off the board.

Another very big contributing factor is how the SMT connector and its board are packaged. If the connector body overhangs the edge of the board and then fits through a nice snug rectangular opening in the housing then most of the mechanical stress of cable pulling laterally will be absorbed into the housing instead of through the connector mounting leads. 

If you have any concerns at all then stick with the through hole part. That is what I do. And on top of that the through hole part takes up less area on the top side of the board and provides good high current connection to the bottom side of the board as well.