It's hard to find good comparisons between the machines. There is a lot of religion among the different camps and misinformation spread by manufacturers to convince people that they have some secret sauce.
Imho there are only a few key differences between Rife machines (leaving out the Doug Coil as it's a different beast).
Plasma/Contact mode - Plasma is like an antenna that creates additional harmonics. So the harmonics likely increase the killing effect beyond what a pure signal via a metal antenna would provide. Contact relies on electrical conduction through the bodies tissues and so may not reach all areas of the body effectively.
Carrier/No Carrier - Some machines piggyback the therapeutic (killing) frequency on a much higher carrier signal. This can vary from 2.1-3.8 mhz for the GB4000 up to 27Mhz for the PERL. Some feel the carrier helps deliver the killing signal more effectively. The carrier also ties into the Plasma/Contact difference as the plasma bulb will have a lower and upper frequency limit so some kind of a carrier is generally needed for that type of machine.
Frequency Range - The band of frequencies that the machine is capable of delivering. Many are finding that higher harmonics of the original killing frequencies are actually more powerful. So a machine that is capable of delivering a high frequency that is closer to the bug's MOR can be more powerful per watt.
Watts - Some machines are more powerful than others. This also feeds into the carrier/no carrier difference as transmitting using a carrier will use up most of the power leaving less for the killing frequency.
I think those are the key variables that result in almost all the difference in effect between machines.
People have achieved remission from Lyme using various machines that differed among all those key points. In the end it's the frequency that is doing the job and the individual machines just deliver it to the body more or less effectively.
Post Edited (project) : 7/9/2016 1:40:38 PM (GMT-6)