The philosophy seems to be to pack a bit more quality than the 420 and maybe people will think that you get a much better machine.
If you think you can have a quality machine for $449, you need to have a reality reset. IT CANNOT BE DONE! This treadmill has too many shortcomings to mention so let's focus on the positive features- mom would be proud of me! It is nicely packaged and it looks like a treadmill. It can make you feel better if your level of working out is buying exercise equipment and sitting in your home. Otherwise, with the elevated blood pressure this machine has the potential to cause, your health might be better off without it.
I have owned this treadmill for 3 years, and I love it and it's abilities! The quality and the price was well worth it! For those of us that want to get in better shape or maintain ourselves without spending $2,000 to $4,000, this treadmill is amazing!