I'm also doing a mixture. My base is Protein Power, which has three versions: Hedonist (the easiest way, not worrying too much about additives and coffee), a middle way whose name I forget!, and Purist, which is almost identical to Schwarzbein.
What I liked about PP is that it isn't as much low carb as adequate protein. With Atkins, you can eat meals that are low in carb, but also below your requirement in protein. One of my favorite light Atkins meals, for example, was a zucchini sliced and fried in butter, topped with cheese. Not enough protein, but legal Atkins.
With Protein Power you have a minimum number of protein grams per meal. Their carb suggestions are very close to Schwarzbein's -- and spread throughout the day, another difference from Atkins, where you could eat your 20 or 25 or 35 (depending on what your OWL level is) all in one glob.
What I liked about Schwarzbein was that it seemed to me to be a plan for life. I've read so many posts about "how do I switch to maintenance" that I wanted to find a plan that is really already maintenance. I want to gradually increase activity, and that means I could theoretically increase carbs as I lose, but the amount of carbs I get now -- up to 15 at every meal -- is fine. If I have more than that, it will be cookies, and I don't want to go there.
So to answer your question, I guess I'm sort of doing strict Schwarzbein. One exception is that I do fry foods -- she frowns on that. I limit cheese naturally, but if I want to have cheese on a burger, I'll do it.
Like Spring, I feel better when I eat some carbs -- mainly 1 or 2 pieces of fruit and 2 slices of a very thin, low carb (and low fat, hence very dry) millet bread, toasted daily. More fiber, perhaps, but whatever it is, I feel better eating it.
I'm all for finding WHAT WORKS
My weight loss is much slower than on previous brushes with Atkins, but it's basically, in the end, downwards.