As for the power issue, my ulterra gives me plenty of warning and I have never had a problem stowing the unit. It would not drive the boat anymore, but still stowed.
I picked up a factory refurbished Ulterra for 1800. Works well with my 988. Also have a Helix 7 sonar only connected to the Ulterra. Very very happy. Just got back from Canada and my set up found the fish and stayed on them all day with spot lock etc. Also made a map of the lake we were on using the 988 and ChartMaster Pro. Set for next year now.