Just to follow up on my initial post.
I did the trip last Monday and based on the replies here, went the $69 route.
The interior of the train looked tired and shabby. Definitely needs a refresh. But the seat was comfortable (I has the two to myself the whole way) and there was ample leg room.
Food was fine and okay priced (though meal selection was limited). Drinks were expensive. So expensive I decided to have an alcohol free day. Unusual for me.
Attendant said there were about 115 people on board.
Transferred to a bus at North Shore. That was reasonably well organised. Got into Southern Cross 5 min ahead of schedule.
Have ticked it off and don't really feel the need to do it again.