Totally agree with this.
Just had a quick scan on the SSI Website does the SSI Advanced Adventurer give you any extra depth qualification like the PADI Advanced Diver one does as that will increase your diving to 30m until you do the Deep Dive Speciality that then increase to 40m.
If not the stick with PADI that way you will actually gain something for the money.
Also the 6th Nitrox dive will not then qualify you to dive with Nitrox it will just be an experience dive to try it out, the reality is though follow the MoD of the gas, breath in breath out thats it its not rocket science
In all fairness though this can happen anywhere not just abroad........
Its also the reason my wife and I carry Epirb's, As do a few other members in the club I belong to.