Don,
I bought the 106 (my second one) with the GT54, bought the GT8/36 and sold the GT54. The 2d is much better with the Garmin, and the down/side is equal to my Gen 2 Mega. One benefit is the Vision+ card I bought for the GPS is as good as the Lakemaster cards, and they share from one unit to another. I currently have a Gen2 Mega SI on my console, Mega DI on my bow, and 106's on the bow and console. The 'Birds are 4.5 yrs old. I really feel that if they go out I will replace them with Garmins. My livescope unit up front I generally use to see cover and see if there are fish/bait in an area. I seldom target specific fish. It is still very beneficial. If I were to make another purchase, it would be a PP Move. That thing is about 25lbs. lighter than my Ultrex and the Force. One thing you will notice is a change in performance in your P2. They are so sensitive to weight up front, it really changes the P2's performance characteristics. But the spotlock makes it worthwhile.