my $0.02
Speed count, aka GTB (for Golden Touch Blackjack) has worked well enough for me, with a few comments:
1. I'm up a decent $ amount for the year, 8 trips.
2. I enjoy several cold brews while I'm playing. I can still keep count very easily while drinking. I'm assuming this helps with cover, I haven't had any major heat issues, even while winning a significant amount one night at a strip facility. I only play DD, I can count the number of times I've lost the count in almost 200 hours of play this year on the fingers of one hand.
3. I have tried other methods (including KO, the KO book is right next to the GTB book in my book case), this one is MUCH easier, but you don't get result as good as other methods, as it's not as precise.
I'm not comfortable posting much more here about my spreads, etc. (long time lurker, new poster), perhaps I'll put more in the Green Chip section.
BTW, If you read the book, he explains the rationale. If you like the theory of why things are done, it's an interesting read.
I'm happy with it. Someone else will likely have another opinion.