I don’t know about any usability dis-/advantages, as this is the only service I have tested. Is duck.com open source? Addy.io is and has an option to self host. And it is not US based. But for most users this might not be important.

I have about 250 aliases and I think I never reacht the 10mb limit. But I also pay for the ultimate subscription so I wouldn’t necessarily notice if I did.

In addition to an email provider I would also reccomend a service like https://addy.io/.

It creates email aliases that forward to your real email address. So you never have to give out you real mail address to any service. If you create a new mail address for every service you use you can easily deactivate it in case it gets spammed. Also you know that the service sold your data or got hacked if the mail gets spam.

Another benefit is that in case the CEOof your current email provider turns out to be a dick you can just go to another provider by changing the mail address where Addy.io forwards your other mails to.