I am totally new to video editing, lacking even the ' good with i Movie' experience which you have. I have recently taken up to learning video editing with this view of providing visual content to my audio albums [I have done 5 albums already and there are many more to come].
I have found Izzy's 26 episoded free tutorials on fcpx a more than sufficient introduction to new comers like me. I have also been helped by participating in the Izzy video forums and learning, learning and learning many things which were new to me. Izzy has recently come up with an advanced course on fcpx, not for free this time, and I am yet to know about its usefulness. But, knowing him by his earlier works, I am sure that his 'students' will certainly rise up very steeply in their learning curves.
I have, with a view to learn more of fcpx and other video related topics, joined up very recently in these Apple forums. I have found these forums to be very vibrant, caring and knowledgeable. Answers given to questions posed are done in a jiffy and there seem to be a number of such knowledgeable and helpful people around to jump in with their suggestions.
I think the best way for you to learn fcpx is by doing this: start playing with it straightaway. FCPX, as with other softwares, has its own HELP centre from which you can get a lot of information which you can hear and see Izzy or others like Larry Jordan explain, or read what Tom Wolsky [he is a very senior in this field and has helped many members with his dedicated solutions and answers] or others like Edgar [you can learn about him by viewing his profile in this forum].
Yes, there are many options before you and you have to make your choice. In the multitude of counsellors there is safety and we should be glad that there are a number of teachers who would like us to be on the higher levels of the learning curve!
DR.SOMANNA