It's not sounding boring that's the problem but trying to write it so that it technologically makes sense because as this thread is beginning to demonstrate, that's not easy.
Depending on the depth in question, if his armor is breached I have to wonder how he survives the pressure.
Servo motors in the armor won't help them move forward much as their feet are small compared to their bodies. Why do you think divers wear fins, ducks have webbed feet and fish have membranes in their fins? Under water you don't need power as much as you need surface area to displace the water and push you forwards (or upwards/backwards etc). That's what fins provide. This is even more important when you weigh a tonne. It's either that or you need jets or propellers.
It's just TDA that is teleporter capable, not PA. Underwater, especially at depth you also have the issue of pressure fighting against you, you move slower. Teleporters won't help with that.
What about all those times humans and standard marines are teleported?