Hi Iñaki,
Good to hear from you! As Michal says we can use the ESR on a dual install, but I do not think it has any major advantage over the swing client, apart from maybe for Java developments.
Is channel activation a part of the ESR or Integration Directory? Either way it is not sole reason enough to make me want to use NWDS.
With NWDS I would want to make use of the ESR and ID together, working hand in hand. It looks like I will stick with the swing client on this dual install.
Che