Salt Mobile tokens are perpetually licensed, and as such any replacement necessitated by loss or user churn does not incur additional token costs. Industry experienced churn rate is around 30% per annum.
Echidna User licensing is based on active users and Salt Mobile tokens are free when deployed with Echidna. As such, as users come and go, and as devices are lost and replaced, there are no additional charges provided the total user base is not increased. Whereas RSA SecurID tokens are not free and token licenses are not transferable to new users.
Salt Mobile tokens never expire whereas RSA SecurID tokens need to be replaced every few years.
ACE servers can only authenticate RSA SecurID tokens whereas Echidna can authenticate multiple authentication tokens from different vendors.
Importantly, Echidna's brokering service allows an organisation to seamlessly migrate from RSA tokens as these tokens expire, thereby eliminating the higher costs of "big bang" migration of tokens.