I'm doing my second year of IB, senior yay, and my HLs are: Mathematics, Chemistry, Biology and English B (yes I have 4 hls...) and my SLs are: Swedish A literature and Economics. So far it's been hard, tough, horrible, challenging, but SO rewarding and SO MUCH FUN, I've got such good friends in school and it helps 'cause we are all going through the same ****, haha, we pull each other through, so I would definitely recommend it, the IB teaches you to think differently and learn in a completely different way, plus I believe that it will prepare me really well to further studies at Uni and so forth, a lot better than any other system. CAS has been something we in my school have to deal with on our own. It's been weird and painful at times, but I think CAS can be great if you make it great. I ran a full marathon (42km) and I've worked with Unicef, taken a lot of photos videos, singing in choir all kinds of stuff. The IB will teach you a lot, and you will get to know yourself better I believe, with like limits and stuff.
It's a challenge. Reach out and grab it!