I use it...and love it!
I, too, was a ploppy using BS for a number of years. Last August I decided to take my game to the next level.
I got and read all the books, got involved on the websites, and was, generally a sponge for information on counting.
Knockout is NOT a sissy in the blackjack counting world. It holds its' own with the best of them. Don Schlesinger has since come around to espouse its' virtues.
You have to remember, KO was not around when Anthony Curtis, Wong, Schlesinger, Andersen and some of the more renowned Pros started. Because they don't use it, doesn't make it an inferior system. Many of them, probably would have, if it was around then. Check Blackjack Attack for comparisons...
Anyway, back to my story. I practiced and practiced and started in the casinos playing KO from the 1st of January, this year. I have played 60 hours using the system and my results are +17 units. Results don't mean anything here, just wanted to show how I have done, since I am relatively new.
Here's something to consider in addition to the other things that have been posted here. Yes, KO is an unbalanced system...and yes, there is less fatigue due to TC conversions, etc...but the best part, I believe is this...COVER.
Most surveillance crews know only Hi-Lo so if you use any system other than that, it will throw them off. Most people don't consider this, but once you get to green/black action, anything for cover helps...
The biggest downside with KO is wonging in. At a 6 deck game you start at -20 and -24 for the 8 deckers...it takes forever, sometimes, to get to a positive count.
I play only DD games, so it is not as bad.
Hope this helps...my 2-cents!