I actually don't like the new 2006 First Aid as much as older editions.
I have both 2003 and 2006, and think a fair amount was cut out in creating the new systems-based approach. Given another year or two, and some student feedback, they'll probably have this approach down, but for now, I'm actually using both.
As many before me who've been successful on Step 1 have said, First Aid is a good roadmap, but hardly a stand-alone resource.
As to Kaplan notes, I actually had a chance to look through the most recent Kaplan lecture notes at our local Kaplan center, and while I spent only about 30 minutes looking through them, I couldn't see any difference between these and the 2002 edition - same material, same review questions, same diagrams. I do think the Path section is weak compared to BRS or Goljan, but the rest seems solid based upon working with it.
Just my 2 cents...