Felix - I'm at about the same point as you, and I had the same thoughts - whether I was "advanced" enough for
PlaneTalk. I can say that it helped my understanding of theory tremendously.....Kirk lays it out in a very friendly, easy-to-understand way in the book, plus you have access to the PlaneTalk forum where he answers questions, offers additional lessons, tips, etc. It's not one of those gimmicky "miracle" master-the-guitar-in-30-days things - you still have to put in the practice for it to benefit your playing - but it's definitely worth the investment, IMO. I had read the "Fretboard Logic" series and a lot of other books, and none of them drove it home for me like PlaneTalk does.