Study the performance of each glass and then compare. Don't buy because of fractional differences, buy quality plus performance.

See the site below to help you.

Michael

Here is a link that might be useful: energy efficient windows

LowE4 is Andersen's standard glass on 400 Series products. They also offer a LowE4 SunII glass, which sounds like a better direct comparison to the Milgard glass you are looking at. The other issue to keep in mind, is whether the figures you view are based on center of glass performance, or if it's the entire unit rating. Center of glass numbers can be misleading if the frame and glazing systems aren't good performers. I know Andersen rates everything based on whole unit performance, but I have no experience with Milgard.
The LowE4 from Andersen has a low maintenance exterior coating reducing the dirt build up, keeping the windows cleaner, which means less cleaning. It only requires good sunlight to activate the coating, and a west exposure will provide plenty of that.
Hope that helps.

There are basically five types of LowE coatings currently on the market.

Three are "sputter" or softcoats and two are "pyrolytic" or hardcoats.

Of the three softcoat products, basic LowE would be considered a high solar heat gain product. LowE2 would be considered a low solar heat gain product, and LowE3 would be considered an even lower solar heat gain product.

Andersen's LoE4 has a standard LowE2 coating between the lites and argon gas for energy performance, but it also includes a titanium dioxide coating on the exterior of the window that makes the glass "self-cleaning".

Although some folks might cringe at the term self-cleaning, the coating does work quite nicely and you will notice a difference in how they look and in how often you will have to clean the glass.

Finally, the "4th" feature of the LoE4 is a plastic film that is applied to the glass in the factory that protects it from dirt and debris and even minor scratches during shipping and handling and install.

Andersen's SunII glass is a tinted LowE2 that has very nice solar heat gain blocking ability and also it is nice because it cuts down on glare as well.

Milgard's SunCoat is a standard LowE2 product - much the same as the LowE2 that Andersen offers as their standard.

SunCoatMax is a LowE3 product. The LowE3 product is very new and has only been around for maybe 3 or 4 months - this doesn't mean avoid it because it is new - it means that it is an advancement of a proven technology and it works really well.

LowE3 has the same heat blocking ability as a tinted LowE2 (such as SunII), but with visible light transmittance very similar to a standard LowE2 product - without tint.

In the case of a west-facing door that has both heat and glare issues, then you may prefer a tinted LowE but with the understanding that the view thru the door will be less.

SunII has either 38% or 40% visible light transmittance (I forget which version they use) and SunCoatMax has 66% visible light transmittance - again with very comparable solar heat blocking capability. Standard LowE2 (including SunCoat) has about a 70-72% visible light transmittance.

Standard LowE has about a 78% visible light transmittance, but it also passes significant solar heat which is an advantage in places other than where you live.

I didn't mention anything about hardcoat coatings because none of the products you mentioned use them. Also, they are much less appropriate in your environment (primarily cooling) than are sputter coats.

No LowE coating has an affect on sound propagation thru the glass.