Has any experience problems with extreme heat or extreme cold weather? Does it effect the performance of the HU?

i have not had a problem with mines form the summer or winten.

correction FROM , WINTER

There's been complaints of the screen not turning on in extreme cold... but that's about it. Same issues as just about any other car stereo product, really. If the interior of your car stays withing the recommended operating temperature specified in the manual, everything's gonna be peachy.