The more precisely w comes to look like -1, the more enthusiasm there will be for cosmological constant theories, which require that value, and the less enthusiasm there will be for fifth forces andmodifiedgravity, part of the charm of which is that they can work with other values.
The four current NASA pilots who can operate the modified 747 are ex-military aviators who split their time flying other planes including zero-gravity aircraft and T-38 supersonic jets.