I agree. The no cry book is more geared towards toddlers so may be better, but I know what suits one won't suit another.
DS hits v rarely at pinnacle of tantrum, if it's gets that far. We've taken the tack of praising gentle behaviour massively, esp with his sister. I agree, just walk away whenever you can. If you can't, then would you consider a special hitting cushion? I know it's not ideal, but sometimes I think their little minds can't cope with their emotions and lashing out is all they can do, so have a special big cushion and just fetch it and punch it together. Almost guaranteed to have you both laughing, or at the least it may break the cycle.
Hitting is a big no no here too, so I am very hard on DS when he does, though it's weeks if not months now. Mummy is very disappointed and sad, it hurts to hit, we must be gentle, come and see me when you're ready to say sorry, then I walk away. At a quiet time we discuss what is good behaviour usually using a story about naughty Norman (from fireman Sam!) and what naughty things he might do and what the worst would be and why that isn't good.
The other big diffuser for us is the how to talk wish list... Sometimes when I get cross I imagine I have something nice instead, like a tree made out of chocolate etc. I only have to give 1 example now before DS joins in, but I had to do some ridiculous ones to start with.
Again though, it's all about prevention really and what I have to continually remind myself is that he doesn't give two hoots about being on time, the concept means nothing to him, so I try to give him warning of why we need to be out by the time the timer runs out. So, DS we need to go to the doctors this morning, if we get there in plenty of time you'll be able to play on mummy's phone/iPad/pop in to shop to buy magazine on the way/etc, so mummy will set the timer when there's 10 mins left and it would make me so happy if you could get your shoes and coat on before it runs out... I don't think of it as bribery, just teaching him that if he helps me, I'll reward that and be happy. Though I admit that the, if you're in the car by the time mummy counts to 5 you can have some raisins, is definite bribery, but is v useful on way to appts!
Also, regular food and exercise are essential.
Sorry, wrote too much...