Jaslight,
I recently purchased the M20S as a replacement for the highly regarded EagleTac T20C2 MKII because the T20 does not have last mode memory.
Other than reading what few reviews existed and deciphering European U-Tube vidoes, I had to rely primarily on the product description to be sure the features I was looking were included.
In addition to hoping for a general purpose, multi-mode light with a balance of a little more throw than flood, I was very intrigued by the side switch designed to change modes after the tail switch turned the light on. Then I noted another feature which was very apealling in that the side switch also activated the strobe from the off position in the event you need this light very quickly as a defensive tool.
However, I was warned against the fact that the current operated using pulse width modulation (PWM) which at low frequencies can show a visible flicker to an individual's eyesight, especially on the lower light modes. Fortunately my sample did not demonstrate that affect.
So for me, this little light is wonderful in being fairly lightweight, well-constructed, with all the features I prefer and then the addition of the side switch was enough to purchase the M20S. In the end, after about a week now, I'm so glad I did, I'm planning on purchasing another. And right now, GoingGear.com has all their Olights on sale at 15% off until close on Sunday, the 10th.
I truly hope my quick review helps you make your decision! All the best on whatever you decide. Feel free to ask me questions here or in a PM.
John