This is a video demonstrating a clicking/distortion issue on the iPhone 6+ loud speaker that most often occurs after the "End Dictation" sound in iMessage.
There is a small chance that this may be simply an issue with my particular iPhone 6+ loud speaker. On the other hand it very well may be an issue with all iPhone 6+ running iOS8.1
Hopefully some other iPhone 6Plus owners will weigh in (via the comment section below) to help me determine if this is a global issue or simply a case of a defective iPhone 6+ speaker.