There is no reason not to expect that they Okna EnviroStar will not hold up perfectly for a very long time.

All windows air infiltration rates will somewhat lessen over time. If a window is well built and engineered, that delta should not be that big a spread and the window should maintain much of its tightness.

+1. The Okna is one of the top performing windows that you will find in any material, and is a stellar example of how a well-made vinyl window should look and perform. I really like the Marvin line of products, however the all-ultrex integrity is a downgrade in this case IMHO. If you are looking at a real wood interior, the wood/ultrex integrity is a very nice choice, however there is really no advantage whatsoever the the all-ultrex has over a premium vinyl choice.

OK thank you the Okna deal seemed so much better I thought I was missing something.

Although not scientific and opinion only, the all Ultrex Marvin a little on the ugly side.