Shark close encounter this morning on OW swim...

Training with my partner Rob this morning off Henley Beach, Adelaide, Australia we were 2k into a planned 8k swim, both of us wearing Orca 3.8 suits and we had a Shark Shield FREEDOM 7 unit on. Near large jetty I got that funny spooked feeling...we had moved into deeper water to get out of the surf break and visibility was very low today from recent rainfall. I stopped and tagged Rob to suggest we move shallower then suddenly a patrol chopper was overhead, hovering low off the end of the jetty. We knew it was a shark spotter and an alarm sounded - beach lifeguards were franticall waving us in, and we did not hesitate to get into shallow water asap. We joined the large gathering watching from the jetty as the beach patrol drove what was a large shark away from the beach in a semi-rigid, what was guessed to be a 6-7 foot White Pointer. We got back in a bit further back down the beach both a little freaked and started back for another leg staying very shallow, then the low battery signal came on the Shark Shield so we called it a day at the beach and headed over to the local 50m pool to wrap up the rest of the 8k. We'll be doing a lot of training this summer off Adelaide and will be putting a lot of faith into the Shark Shield units. Anyone have any experience with them? Todd