To be fair you'd only be using one or the other, `%%` for jvm-only, and `%%%` for cross platform jvm/js builds.

Far and away the biggest blocker to learning sbt is the shaky IDE support for the build project. Apparently that's coming up next in 1.0; will be nice to click through to source from sbt build files and instantly grok what X symbol means. Have wasted a lot of time over the years slogging through documentation...

A build definition format that allows arbitrary code anywhere is always going to have less-good IDE support than one based on declarative documents.

I don't see why, as long as the IDE sees the build file as a genuine source file for the language it's written in.

The IDE would need to run it to understand the build definition, which then gets into halting-problem issues.