I finished FbAdventure today! on time! I am really happy :D
FbAdventure is not the most popular FB program, and I would call it the most under rated. 4 solid difficult workouts put together so wonderfully, along with extra credit almost all days. In fact, you can make a solid extra workout day just accumulating all the extra credits each week. I just did Fbburn r1 last month. I definitely found FBAdventure much more challenging in terms of difficulty level, especially if you add up an extra day of activity of your choice. And it is heavy on strength training which I really liked. If you don't want/have time for 5 days, and still want a solid program, go for it!
Now come to the second topic. I don't have any knee injury, but my left knee doesn't have the same muscle build up as my right, most probably because of my asymmetrical walking. And it causes weakness and slight pain time to time. Last month while doing Burn r1, I realized my left knee is always uncomfortable to the point that I wasn't pushing any pressure on it while jumping. So reluctantly I forced myself to go low impact for this program. What I did to compensate this is to lift heavier and making all 8 reps to 10. And boy it made a difference! My squat lifting increased from 24lb to 36 lb total, deadlifts from 36lb to 48lb total. Also, I was more mindful about posture as I wasn't scared of hurting my knee with jumping. This "rehab" process made me able to return to high impact partially by the end of 3rd week. And yesterday I did star jumps with Daniel without any trouble! :)
So, here is my 2 cents about going low impact- throw away the "vanity of high impact" (if you have it like I do!), if your body needs it. There are many ways to challenge yourself even without jumping.