All I can say is that I had been working out faithfully for 2 1/2 years (with 3 months off for broken shoulder in 2011), and I thought I was in pretty good shape, only want to lose about 10 more pounds (some say I don't need to, but you know how that is...). Anyway, I thought I would whoop HC workouts just fine....but let me tell you.... I was in for a rude awakening... My problem was that I had good cardio endurance but my aba and upper body were lacking.
Therefore, my advice to you is that unless you have absolutely killer abs strength and upper body strength, I would get at least one of the three intro workouts.
Another test you might do is....can you do a plank for at least three minutes? Can you do at least 32 full body push ups at one time?
If you cannot answer yes to either of these questions, you might consider getting one of the intro workouts.... Originally, I got HC2 and it was just too much for me,so I had to remediate and I got getting stronger which is tough too.
I got my first HC2 back in May, then ordered Getting Stronger. I just finished STS double time and now I just did HC2 again on Saturday...I am much stronger now and was able to do it, but I did modify it a bit still!! And it is definitely still a challenge!
Actually, I am going to start a new rotation of HC 2x per week because I just finished sts.
Best wishes....