MW Sash Replacements

[kooshball]

What is the story with these? They are half the price of Jeld Wen and Marvin's inserts which makes me concerned for their quality. Any known issues with these; are they going to perform about as well as the MW 3/8" thick units that were in my home originally (i.e. fog up in 10-15 years) or can I expect that quality has improved over time?

Thanks