Well, as far as advice goes, here's what I can muster..
I usually play with contacts on, yet don't use them to evade after an attack.
It has become a habit of mine to leave the Obs scope upe some inches and use it to look around underwater while evading. On my Sargo, I crank it up a bit and then turn it to 180, then crank it up to that point where the radar antenna is just on the lower edge of the field of view. At 100-200ft, this angle lets you look at the zone any escort will have to move through to drop DCs on you. As soon as I see its Bow, I know how he will pass, hit flank speed and steer out of it's path, always going up to 100ft depth while doing so. As soon as he is out of sight, I get back to slow ahead and let the DCs go off below and behind me. If another one comes up into view too quick or I am being pinged while the other one makes his pass, this is the point i use a decoy.
After that, regain depth to just below the layer and hide again until you see the next escort making its run. As long as they're making a DC run, they're deaf and not using active sonar anymore. If one just made it's pass, one is coming up and you still get pinged, you got three or more escorts up there teamworking. In that situation, I have the habit of instead of using a decoy, going up to PD to take a shot at them before going deeper again. Scares them off pretty good most of the time.
Maybe some of this'll help you out.
