I agree; I see the two services as complementary. I use Instapaper to keep track of writings that I intend to read. I use Delicious (and/or Pinboard) to file

I agree; I see the two services as complementary. I use Instapaper to keep track of writings that I intend to read. I use Delicious (and/or Pinboard) to file away URLs that I intend to refer to. (Secondarily, I use Delicious/Pinboard to share links with the minority of my friends who also use the service.) What really bums me out is when an app that I like integrates support for one service but not the other.