Can't add much that I didn't say before. I pinged Oberon for you and hopefully he will pop in.

The Starmark should be the pretty clear winner as performance goes both thermally and structurally once you have all of those numbers aggregated. The Infinity is a nice, well built unit, as well, just not in the same space efficiency wise, although there could be other options that could point that direction for you like a stainable or other color painted interior.

Not familiar with Vistamark.

Milgard is decent, it fares well against the many less than stellar units offered on the West coast. Not quite as well IMO when going against some of the cold-weather-born unit in the East and Midwest.

As far as the certifications, as mentioned on the other site they are nice to have, but I wouldn't get hung up on them. Installation Masters specifically is more weighted toward new construction installation. In remodeling work, there are so many different circumstances to deal with that experience is what makes the biggest difference. The history, general reputation (reviews etc), association with a quality manufacturer/product on a direct basis should all give a good indication of the quality to expect.