I have been using this circuit training for 2 months and it shows good results for stamina and general physical condition. After it the muscles are not overloaded, so you can still do some additional strength excercises or tire striking for technique.
I think it is medium level as for our "youngsters" it is rather hard, but still it is not as hard as a WOD.
I think my intensity for tire striking and for punchbag was something like 75% from maximum (you can't actually work here like in tabata).
Hint: if you want to feel the good results you must choose the heavy weapon for tire striking, heavy kettlebell (so it were hard for you to work with for a minute without stops) and a heavy hammer.
You can change the excercises, but remember that the main thing you need to pay attention to is not to overload the wrist as that way you will not be able to strike tires properly. And you need to choose excercises in such a manner so all muscles groups could work.