It's been my experience that while FC will save you time upfront, Anki will save you time in the long run. I tried using FC from the very beginning. IMHO, their questions are complete crap. Many are vague, poorly worded, and not amenable to spaced repetition. And it seems that the company is more interested in branching out than they are in improving their existing products. Like the above poster pointed out, spaced repetition is meant to be done fast. Most (not all) FC questions are far from that. So while you may save time initially, you'll find lots of people who begin FC with good intentions and later find the time commitment to be too much. And, make no mistake, these people who drop out aren't just lazy. But FC isn't all bad. I'll be the first to admit that their cards are nice and generally well written. I've definitely picked up some integration facts from FC.
On the other hand, while Anki works for me, I don't think Anki is for everyone. You'll run into the exact same problems as FC if you don't know how to write questions correctly, even with using FA as a guide. Maybe I'm a slow learner, but it took me several starts and stops to be able to write good questions for Anki. Even now, I'll occasionally have to remove or edit a card because it's just not written well enough for regular use.
For the record, I have a subscription to FC, but I primarily use my self-written cards on Anki. I like looking over the cards in FC because, as mentioned above, the content is good. However I can bang out my self-generated questions, faster and with better retention, using Anki. I've been using it since last summer and add content immediately after I finish a module. I have zero complaints.
If you decide to use Anki, this should be your guide in writing questions:
http://www.supermemo.com/articles/20rules.htm
Yes, it looks like a geocities webpage nightmare out of the 90s, but the content is top notch.