Well, I think I have to say at this point that the caveman regimen isn't making a big difference to the number of spots I'm getting.
What it has done is reduce how red and big they are, how sore they are, and how long they hang around.
I've decided at this point, that although I am going to continue with the caveman for the foreseeable as it seems kinder on my skin (and I think I am still in the adjustment phase and I'm interested to see how it progresses), I'm going to be focusing more on my diet.
I've been talking to someone on acne.org about diet and they referred me to this study (there are many others by the same author), implicating sugar, dairy and meat in the formation of acne. It's a heavy read, but worth it.
I'm not sure exactly how/where I'm going to start, but I've always noticed an improvement when I cut out the sugar, so maybe I wasn't being diligent enough or looking at other causes simultaneously (like dairy/meat). Acne seems to be a very complex thing and I know from my own experience that there is no one food that you can cut out that cures it (tried that many times).
Anyway, going to have a think and update soon.