Honestly, not sure outsourcing communication with tax authorities about returns we prepare to some third party is a good idea at all, especially those that require complex technical analysis.

Many a time, even IRS agents need to escalate to higher level for issues they don't understand, let alone some third party who have no source documents and context.

If this is only for run of the mill returns, it's probably not worth paying for firm-level protection.  But then at close to $50 a piece ad hoc for 1040, I dunno...