A.J. Keller & Peter Gamma from www.petergamma.org – what are their similarities & how do they differ?

The similarities are: Both use a biofeedback-assisted meditation devices A. J. Keller uses the Neurosity Crown: Peter Gamma from www.petergamma.org uses a Garmin watch: but Peter is not happy with this device, since it is only of very limited use for scientists like him. But how do A. J. Keller and Peter Gamma from www.petergamma.org …