I can confirm that the Companion Ticket does NOT work on Saver fares in the NE Corridor, contrary to the information in the wiki. I tried to book a WAS-NYP itinerary at the $49 (common) saver fare level, and the AGR rep on the phone said that I could only use the companion ticket if I purchased the "full fare" $88 regular fare. Pretty much makes the companion ticket useless for the NE Regional. Might be a better value if used on Acela, since I usually don't see saver fares for those.