Playerships using the maneuverability attribute for 1.2 or earlier display a maneuver rating of 7.5 regardless of their maneuverability and in game turn at that rate. It would be more difficult to test NPCs, but since this appears to relate to the deprecation of the maneuverability attribute I would expect it to apply to them as well.
The old maneuverability attribute needs to be supported in any mod up to API 19 even if the new syntax is to be required under API 20.