Well, I just put a Xantrex in after the Magnum failed after 2 years. I sent it off to Magnum last week. It also has a 2 year warranty, except if you have a monitoring panel, they extend it to 5 years.
I'm hoping there was nothing wrong with the Magnum and the issue (not inverting) was a bad ground as I suspected when I took the MH into the shop. The shop put 2 inverters in before they chased down the grounding problem. If all goes as expected, Magnum will fix the unit and send it back. I will leave it in a box in the garage so when the Xantrex fails, I can have my neighbor send it to me.