Currently you seem to only support stronger authentication options for those customers who use Duo (under their own contract). While we would be OK with an Aha! contracted strong authenticator, if we must supply our own then our preference would be to use LaunchKey, our own best of breed strong authenticator that we already use.
Thank you for your idea. As noted, we do currently offer two-factor authentication through Duo. At this time, give historical feedback and current priorities we are unlikely to add additional options. We hope you can understand.