We have had Karma for over a year now. We have spent 220+ nights on board which I would have to assume for a non-liveaboard is more than anyone else. We now have 315 hours on the motor.
We have the Xantrex Inverter that the factory installed as well as the Nautilass AGM batteries. We did have issues with having one bad battery within the group of four for the house. Once that was taken care of, we have had no issues with the batteries.
We have had no issues with the Xantrex inverter other than the massive amount of power it wants to draw when it is in the battery charge mode. This was solved by installing a Xantrex Power Share system to regulate how much power it could draw.
We use the inverter everytime we unplug from shore power with no issues so far.
Just like everything else in life, if you have the means to purchase the best, do it. If you do not, buy the best that you can with what you have. If I had to do it over again, I would take the Xantrex.
The only change I would make to the electrical system would be to install 50 amp service. At 30 amp, we have really had to learn what you can run and what you cannot run at the same time.....