$1099 or $1999 is the difference in cost between the 24-105 II as compared to the 100-400 II. Apples to Oranges
$999 or $1099 is the difference between 24-105mm to 24-105 II. Apples to Apples
When I want an apple I am not interested in oranges.
No offense but no one is paying $1000 for the 24-105 Version 1. You can get them brand new from a kit for $500-$630 so the price gap is pretty big in my opinion and the improvements are not worth the upgrade.