Motorola's Schuster says Android 6.0 test for Motorola Moto X Pure Edition (2015) is not a soak test
While Schuster said that a soak test for Android 6.0 has not started, he did say that a TestDrive for Android 6.0 has begun for the Moto X Pure Edition (2015). This small test will be run for a couple of weeks, and the feedback that Motorola receives from it will determine when the soak test will begin for real. The TestDrive does indicate that Motorola is thinking about the update, which has to be good for those toting a Motorola branded handset expected to be updated to Marshmallow.
If you're interested in being considered for a soak test, you need to be a member of the Motorola Feedback Network. You also have to agree to a confidentiality clause which prevents you from discussing soak tests with the media. As long as Motorola's Schuster keeps us abreast of what is going on, that media blackout shouldn't matter.
source: +DavidSchuster via AndroidAuthority