In my personal experience (as a contractor having used both), I have had more success with the Infinity.

The Ultra is a solid product but I have had several service issues with the installed products that we have done in that line whereas we have had zero with the Infinity.

I think the Infinity has a cleaner look as well.

Would you mind expanding on the service issues you are referring to? i.e., is Milgard not honoring their warranty or dragging their feet, etc.

Also do you feel that fiberglass is a good long term product?

Thanks.

There were a couple of issues on one project where the windows were not sealing properly when they were installed plumb, true, and square. These windows were adjusted and re-adjusted to ensure exact fitment.

Milgard did not view it as a product defect and the air that was leaking was claimed to be allowable, however, the customer and I were both unhappy with the results. That cost me money.

The sample they shipped me for an in house demo didn't work right as I pulled it out of the plastic for the home owner.

Their service team damaged a window while trying to get a sash out and claimed it was the customer that had done the damage. They actually used a kitchen utensil (expensive knife) to remove one sash and damaged the knife in the process.

The factory service aspect may be great on the West Coast but it was a liability on the East Coast.

Thanks for your followup.