Personally, its worth spending the extra. I can tell you this, the Xenarc is more automotive friendly on a few stands. But to point out a couple is auto start - aka, you don't have to turn on the screen each time you start the car. Two, its brighter and simply easier to see in the day light. Much easier? No, but easier, yes. ahh, what the heck, and 3rd reason would be no need to regulate input power voltage. The screen will support with no issues the direct power feed of your cars power line with no regulation. Course, you can if you insist. WIth the Lilly you must regulate.
Guess it comes down to your priorities and your setup.