This is all a matter of opinion and I will give you mine. Technically, you can say that a rep only represents the pilots that elect him, i.e. his base. If you want you can even say that the ATL Captain reps only represent the ATL Captains. However, my opinion is that the MEC works best when each rep considers the interests of every pilot in every decision they make.

If we look to Congress, we can see the most hateful practices are those when a representative or senator brings home the bacon to his district or his state. They quit representing the entire country and they think only of the interests of their electing body even if it harms the entire country. We all know the stories and I want to avoid violating the political TOS of this board by getting into specifics, but it is safe to say a pox on both their houses.

When reps start to consider themselves as representing the ATL pilots, or the captains, or the senior pilots, or the narrow body pilots, that is when the MEC breaks down. If you look to the way the Delta MEC handled the distribution of $2 billion in bankruptcy returns, you will see that there wasn't some battle drawn by any demographic group. By looking out for the entire group we avoided the politicization and balkanization of pilots into "factions".

Every vote a rep makes affects the entire 12,000 pilots, therefore they have to consider the effects of their vote on every pilot. We elect reps by base and seat to ensure that a variety of opinions are heard. As I said before, internal conflict enhances the quality of the MEC work as long as the conflict is kept internal. No one wants a bunch of yes men but no one wants to have debate stifled and suppressed by fear of public retribution. The MEC hires people to staff the administration to provide support and recommendations to conduct their business. If those people are cut off at the knees for political expediency, you will find the quality of that advice drop dramatically. Any MEC rep that publicly admonishes a member of the administration is a poor leader in my book. Praise in public, criticize in private.

So my opinion is that regardless of the base or seat you were elected from, every rep needs to consider the interests from number 1 to number 12,000+ in every decision they make. When that breaks down, the MEC breaks down.