Wouldn't it be interesting if the attacking force had a choice between keeping a starbase for themselves, rather than destroying it?

All of the starbase's defensive modules would be destroyed, of course, since they would need to do so in order to subdue it.

Once you had 'won' in a battle against the starbase, you could have two options:

1) Keep the starbase with all modules, minus the defensive ones.
2) Mine starbase (destroy it).

I think it would offer an interesting twist in warfare - you could capture resources instead of simply depriving the enemy of them. Influence starbases could be turned around for YOUR benefit. And pumped up economic starbases could be kept in working order to give that much-needed boost when you overrun their nearby colonies.