Thanks for all the feedback. Its good to get perspective from people who have actually done them.
I work full time also so maybe doing these two together might not be realistic with work. I do enjoy the calculation side of things more than theory but it sounds like I would be completely swamped in numbers and there is the potential to get extremely confused between the two.
I will probably pick one and of them and do F8 also. Nikkie what did you do F6 with or did you study it on its own?