Lab Requirement in AP CS A
I looked at them when they first came out and decided not to use them. Did go through and look at the topics and make sure that we're covering everything we need to in class. But between labs that I've written or purchased we've got a pretty good set of assignments that covered everything that the AP provided labs hit on.

The 3 AP labs also lean more towards projects instead of simple labs. I prefer to do a lot of small, single method labs. Especially early in the year. We do larger scale projects later, and they overlap a lot with what AP provides.

And not really part of your question, but I can't imagine only spending 20 hours on labs through the year. We probably hit that goal within the first month of the year. 

Edit

Following up on a comment asking about lab sources...

The best labs are past AP exam FRQs. My goal every year is that by the AP exam we've done every past FRQ in class as a lab, quiz, or test. We start in September. Going back to 2004 there are 45 FRQs if you don't include the GridWorld ones. I generally assign them as in class assignments though since there are solutions posted everywhere online. If they're assigned to be worked on outside of class they'll be daily grades which have very little grading weight in our district.

Another good, and cheap, source are programming packets from old contests. UIL, the organization that runs academic and athletic contests in Texas, sells past tests on their website. You can buy a PDF with all the tests from a year for $4. There are 5 or 6 tests a year with 40 multiple choice questions and 12 programming problems in each test. Only downside is that they're not sorted, so you'll have to go back and figure out where they fit. And some are more data structures problems instead of AP-A. ACSL also sells past contests on their site.

And our district buys curriculum from A+ Computer Science. Best thing here is that it's a complete curriculum - labs, project, quizzes, tests, slides; everything. I use this mostly for the written tests because I hate writing multiple choice questions, but I also tweak some of the labs a little and use them.