Fingers crossed G2N is repaired.
Well it appears Humminbird has fixed my problem. I installed my second replacement (3rd overall) Helix 10 GPS SI mega G2N head unit and my troubles are gone. Ran it all weekend. There was only a couple quirks but they came only when I was in extremely shallow water less than 2 foot where the screen read 13 feet deep but the bottom image showed the actual 2 foot. This would bounce back and forth every few minutes and correct itself. I will keep my eye on this.
The actual techs and reps were very helpful during this 6 week ordeal given the cumbersome and time consuming corporate policy they/us have to work thru. Its a shame that in my case 2 of three head units were faulty units. Hopefully for everyone elses sake, I was the unlucky exception and not the rule. Although I did run into a guy on Enid Lake this weekend that was having the same troubles as I.
All in all, I am very happy with the finished product. Next time, I will wait and buy older technology that has the bugs worked out. Now I just need to save some more money so I can upgrade my map cards.