Thanks for the heads up on this thread.
Regarding a check option via Authorize.Net. s2Member Pro does NOT support check payments through Authorize.Net. The last time I checked, Authorize.Net did offer to support checks, but it was available through a sister company, and a different API. One which has not yet been integrated with s2Member.
Honestly, we’re not anticipating the addition of ANY echeck APIs into s2Member’s arsenal. From past experience, eCheck APIs are not well suited to membership sales in our opinion; and in recent years, it appeared to be a method that’s being phased out as a viable payment option online.
FYI: PayPal does accept check payment via a PayPal account which is funded by ACH transfer. It’s not quite the same thing as accepting eChecks via an eCheck payment form, but it provides a safer, more effective/stable alternative in our opinion (from a merchant perspective).