The only thing the kiosk can do that can't be done from your home is scan your fingerprints.
You can get free fingerprint cards from atf.gov, roll your own prints, mail to Silencer Shop.
Understand that Silencer Shop is not a retailer. While they let you choose a silencer, add to your cart with trust, accessories and a tax stamp.....YOU choose what dealer you want to receive that silencer. Each of the dealers on their website sets his own pricing....not Silencer Shop. Pricing can vary from $0 to over $200 difference.
Price is one factor, convenience is another. But also of concern is whether that dealer understands eForms and has experience with them. If he doesn't....find a dealer who does.