I'm a mail filer. Sent via Fedex signed for. Received hardcopy NOA1 18 days later. Biometrics were reused. Interview scheduled 4 weeks after NOA1. I filed via mail due to income waiver, no other reason. Would have loved the convenience of filing online but it doesn't seem to make any further odds - as Dashinka stated, you have an online account, and you'll still need to print the entire file off for interview, regardless.