I can't answer your question except to advise you not to get Pella sliding glass door. I just replaced my Pella sliding glass door, which I detested. Pella's "patented design" means the track is on the outside. This is really bad if you are in a snowy climate (like, e.g. Chicago or Lake Tahoe). For that matter, even if you are not in a snowy climate, the track on the outside is poor engineering because debris and insects get in there, and also it is easier to break into. I replaced my Pella sliding glass door with a Marvin, and couldn't be happier. It did cost $$$, and I got a wood not vinyl. I wanted a durable, heavy-duty, beautiful sliding glass door, and for that, I had to pay up.

I am sure someone else can more specifically answer your question, but I just wanted to warn you away from Pella sliding glass doors.

I just replaced my 8ft slider with a BetterBilt from Lowes. I live in a harsh (salty) environment and these work fine for down here. The only thing I am unsure about is snow against the door. I have a threshold which is 2" above the patio floor so I don't really have to worry about water coming in through the door. Not sure if this is an issue with sliders in the snow?

Just to give you an idea: Slider was $750 from HD, $450 from Lowes when using a 10% coupon at both stores. That's 96x80, Low-E with IG and aluminum frame with screen. I'd definitely go through Lowes again for the better price.

I'd buy the Marvin Integrity French Sliding Door if it was my vacation home.

Any experience with the Marvin Ultrex window in cold, high elevation environment?

From my experience it should not be an issue at all!