Again,

ATL, Intl ops, second airframe etc are all things one airline brings to another and has little bearing on SLI.

SLI issues deal with what each pilot group brings to the table.

Look at it from an individual perspective;

As a line pilot, am I appreciably impacted by whether or not I fly to ATL or out over the water? (I'm not talking about revenues, additional cities etc, these are all company benefits).

Not really.

Now, ask yourself how you are directly impacted by things like;

Seniority?
Pay?
Retirement?
Benefits?

I'm not trying to throw down a "we have more to offer than you" line in the sand - but these are the items primarily focused on when negotiating any SLI.