As I said in an earlier post - there is no doubt whatsoever that a rife machine could/can harm a healthy cell - it's a combination of frequency AND power.
If the frequency being used is at the resonant frequency of a desirable cell then it will affect that cell in exactly the same way as it would affect a "bad" cell if you are on its frequency.
When power is brought into the equation, it gets more concerning because enough power will overcome pretty much any cell in the vicinity whose resonant frequency is close. Consider that if the "power" of the cell is possibly in the microwatt/picawatt vicinity (I'm guessing) - then even one watt is going to be thousands of times higher than what it is used to.
The other consideration is the delivery method. Tube units HAVE to put out huge amounts of power because of the losses involved before the transmitted frequency gets to the desired area. Radio frequencies are much lower so they penetrate more deeply at considerably lower outputs, and if you are holding cylinders in your hands then you are getting the maximum delievery - appreciating that there will still be losses incurred before the radiated energy gets to the target.
For whatever it means to anyone - I am an ex military electronics person and have worked in the fields of electronic, nuclear, bacterialogical, and chemical warfare, and while I don't see auras in people - I do see "energy."
To wind up - I have been using a GB4000 with incredible success and the only thin I disagree with regarding the preprogramming is that absolutely everything is done under square wave. If you want to destroy stuff - I'm square wave all the way but if you are wanting to support stuff (eg DNA repair or the endocrine system) then I find sine wave to be a much better proposition. Just my thoughts - hope someone finds them useful.