Having hired both a 7720 and a 1440, I would say the 20 series deere will leave a lot less wheat in the field, and if you want the straw you will get more bedding.
In beans, the 1440 will have less unthreshed pods, but more dirt... and when questioned on this the IH operator said, it getting all the fan its got.
The engine in the front is not good on the deere. You could look at it this way though- If she gets on fire, you'd be the first to know!!!