Hi Anita .....
The way I understand it, the two devices (Oticon Medical or Cochlear) work on the same bone-conducted principle of transferring incoming sounds from the location of the processor to whatever auditory nerve is still working and capable of picking them up. As far as I know, the SoundBite (made by Sonitus) works on that same principle, as well. It conducts the sounds via the appliance on one's teeth (from the behind the ear receiver), which conduct to the bone.
Your doctor should be able to tell you the status of your auditory nerve(s), as to whether a bone-conducted hearing device is appropriate in your situation. If an AN patient's auditory nerve is not working on the AN side, I do not think it matters which surgical approach was used. Translab is the only one that automatically and permanently causes SSD, because the cochlea is removed during surgery.
For what it is worth, I retained 20% of usable hearing following my first (retrosigmoid) surgery, but lost the remainder with the translab. I used a traditional air-conducted hearing aid for the time between the two, although at the time of my pre-second surgery audiogram, I was already losing some speech discrimination.
The choice between Oticon Medical's Ponto and Cochlear's BAHA is basically a personal decision based on your assessment of the sound quality, appearance of the devices, additional "bells and whistles" options, reputation for servicing, patient satisfaction, etc.
Best wishes. Clarice