Been awhile since I read that story, but I know they never actually fought during it.
And Morrison also had All Star Superman defeat Solaris. Yeah, technically they're in different canon, but Morrison dropped a lot of hints that the two were part of the same arc, unofficially..
The Solaris that All-Star Supes fought was vastly different (from a power standpoint) than the version Superman 1M fought. It would be like comparing the strength of a newborn baby to the strength of a full-grown adult.
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
You're assuming Sun Eaters in the All-Star universe are the same as Sun Eaters in the mainstream universe. Based on what was shown, they don't seem to be.
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."