IMO...Systema has some very good movement principles and foundations, but it has been marketed to death and promoted with dubious/contradictory histories. I have read so many contradictory accounts of systema's history. One article I read in JAMA claims it's long ancient history as "Russian Martial Art" yet the recent ad in grappling magazine claims Ryabko is the founder of the system. You can't have both. In my limited experience with systema, it so distanced from practical fighting/training against resistance that is has become more of a Russian fitness or aikido program than a practical combat system.
Unfortunately, in North America, Vasiliev is becoming very rich through mass marketing the crap out of systema. Distance learning, easily attained (and expensive) instructor certs, combat training camps for weekend warrior types, etc. I really think that any system that must depend so much on pushing it's "Special Forces" connection, rather than it's practicality, must be suspect. People should train in it because it works, not because you can run around the Canadian woods with fake AK-47s dressed in camoflage. Join the army if you want to do that. He is selling a "Russian Fantasy" and people are eating it up. Sad part is that Systema actually has some very valid principles.
I have met and traind with Vasiliev (and some of his top/oldest students) and he is the real deal (I even have footage of him working out with my sambo coach). Some of Vasiliev's senior students that I have met actually have voiced sadness over what is happening to systema through mass marketing. Vasiliev is killing the art while making himself rich. I do think systema has practicality when it's movement philosophy is used as a supplement to other training but, be honest about what it is.
What is the difference between Systema and Sambo? Big difference. Systema is an offshoot of combat sambo. My own coach, life long military and nearly 70 years old now used to say that systema was a less practical offshoot of combat sambo. He never said it was lacking value, just that it was not what it is marketed to be. One of my student's grandfather was a Russian Special Focres during WWII (Black Death as they called themselves - the term spetsnaz only came about in the 1970's). Many of those guys were navy folks who were re-trained for special ground ops after their fleets were decimated by the Nazis. In any event, when my student asked him about systema and the Russian Special Forces, he laughed and said he never heard of it - it was always sambo.
I also ask, why is Putin not putting his name behind it? He is very honest about his combat sambo background from his career in the KGB. He is the first one to support sambo and promote his connection to it. He did not put a "systema" section in his judo book, he put a combat sambo section. He never mentions or promotes systema.
Honestly, sambo's history is full of questions and contradictions too - thanks to the secret soviets. But, it is still mentioned for 70 years in some fashion or another.