though i don't ride a recumbent on one of my bikes i recently purchased a felt, i put a compact crank 170- 50/34 and a 11/25 cass.
i have always used 172.5 cranks and 11-23 cass. it is a hell of a lot easier on your joints and for me it helped produce a nicer spin more fluid lie more of a smooth pedal stroke What i personally noticed with the 172.5 cranks there was a lope type affect coming from the dead-spot to the top, with the 170 crank it is far more fluid and constant