I won't speak for all of us, but I find that SFQ has everything I need. I've made the choice to use it throughout my life. It is a guide I constantly refer to as I travel the path of self-mastery.
SFQ was my first introduction into Qigong, however I've done some other reading since learning SFQ. I have found some additional knowledge in the other material, but little if any enlightenment on the fundamentals. I will say that the fundamentals are in the other systems, but I find them harder to discern amongst the exhaustive instructions.
Just last night, I was going through a book I picked up at a used book sale. It was title Kung Fu and Meditations. Well it's really just a bunch of proverbs to meditate over. Following a system similar to the 108 moves fo Tai Ji, that I've only heard about.Just to share some of this recent knowledge (para-phrasing).
No one is enlightened, some are more enlightened and some less.
The more you know, the more you need to unlearn.
I recommend SFQ to many of my friends; three of who have borrowed some of my materials. I never push, since each persons path and needs are unique and only they are best able to judge what is right for them.
Would I recommend it to you. I recommend it my friends, I'll do no less for you. Yes, SFQ is well worth your time. Master Lin says that a person should follow a system that they feel is correct for them. He also says that if you wish to advance in qigong you should follow a single system until your have made significant progress, before you follow others. He does not say that his system is the one you should follow.
Now how do you know which system is BEST for you, without trying them all. Well my understanding is that there are over 2000 systems, so you're not likely to try them all. My mathematical side says how do you know what definition of BEST is BEST for you(It's okay if you don't get that). My recommendation is that try a system and if it feel right for you, then stay with it until you've developed your abilities and then you are better equipped to navigate your own path. If SFQ or the system(s) you tried don't feel right, then keep looking.
You will find your way correctly, you are being guide well, but you must stop thinking and start walking or else you will remain where you are.
You are perfection.
Iam2