I used the 4000 for a number of years, but found that it was causing problems in my right shoulder. The reason is the inclusion of a full numpad makes the keyboard so wide that your mouse hand has to sit really far to your right, causing your shoulder to be in a position of constant rotation and eventual strain. I eventually took a hacksaw to it to remove the numpad, which improved things - but it was the main reason I preferred the successor (sculpt) as the numpad is a separate detachable piece. These days I'm a split keyboard ergodox weirdo because it lets me put a trackpad in between the keyboard segments which means my shoulders can stay in a neutral position the whole time