I haven't seen it first hand, but lots of our current customers ditched them (and others) after working with their APIs or lack thereof (#xml).

In general, ACH just wasn't built to accommodate "platforms" as an entity in the transaction cycle. Banks, while although cheap, have a problem reconciling their infrastructure and processes with today's expectations. Not to mention their services don't package or include other compliance required to leverage ACH legally (KYC, OFAC, reporting, reject handling, etc.).

Bottom-line: ACH and traditional providers are not suitable options for today's platforms. Among others, banks are hemorrhaging ACH-related business to companies like Stripe and Dwolla.