There are some missed Features in the Nexus :

Coupone
Affiliates
Domain Integration is very poor




i hope that they will be included in the final version

I would change your signature if I were you.

http://forums.invisionpower.com/index.php?showtopic=274141

I remember a while ago, but coupons etc. were planned for 1.1 of the billing module, unless that changes when they re-evaluate I do not know.