The last time I used NYOP for air was in April 2001. At that time, there were $50 bonus links for booking air. I booked 2 tickets at the time: LAX-PHX & LAX-SFO. With the bonuses, it cost less than $100 for both tickets.
On the PHX-LAX trip, UA oversold the flight & I collected $600. ^ Flew out the next morning & got to stay in nice hotel.
The drawbacks on the NYOP were flights can be nearly anytime during the day. I think I had afternoon outbounds & morning returns. (That was Fri-Sun days).
If I had no status & didn't care much for time of day, airline, etc, NYOP air may work fine. I like my upgrades & double miles so I haven't done one since 2001.
Very interesting thread.