Shotgun microphones aren't very useful when you're all the way into the reverberant sound field. At that distance the angles at which sound reaches the microphone are close to random due to all the different reflection pathways that occur, so the great majority of sound energy reaches the microphones from off axis.
Shotgun microphones have poor high-frequency response off-axis since that's essentially what their design is all about! The interference tube is designed to cancel as much off-axis high-frequency sound energy as possible, so that the high-frequency pickup will feature the direct sound as much as possible.
Using them beyond a certain critical distance (where the direct sound is swamped by reverberant sound) isn't what they're for, and they don't reward that type of use. A pair of good, small supercardioids will generally make much better sounding recordings from far away than shotgun microphones will. Even cardioids are preferable to shotguns when you're forced to record at a great distance. A diffuse-field-equalized omni is preferable to a shotgun for this application, for that matter.
--best regards