I think the big advantage of the Rpi or Rpi2 (for speed, memory and cores)

is that there's a wealth of published projects for them, including hardware ones, and other stuff,

and they aren't likely to go away. It's true that lacking SATA and Gb Ether makes it harder

to use them for certain applications (except as demos, alhough there's a Kickstarter project for mSATA),

but if you're doing Computing in the Small both SATA and Gb are perhaps optional.

I'm glad you asked, though, because I hadn't seen the APC Paper.