Here's the scoop.....
Michilins will be better for you since you're in the dry heat more than the wet slop we have in the North East. Spend the money, It's worth it. The tred will last long if you're easy on them They're a little harder riding tire than the Continentals because they don't give as much nor have the tread depth to help absorb the rocks and such.
The Continentals will last a little longer because they have a lot more tread depth than the Micheline tires. Plus as I said before they're a little more comfortable.
As for how long will they last? That depends on how hard you use them.
I would in no way stear away from the factory recomended tire ratings on any vehicle, let alone a piece of machenery as fine as this. These cars are engineered with a lot of things in mind and the tires are a very important piece in the suspension.
YOU GET WHAT YOU PAY FOR!!!!!!!!!!!!!
Don't scrimp on quality.