, thanks for the test drive!
The Cabal version thing buildwrapper can do nothing about. It uses the GHC API which requires the version of Cabal GHC was installed with. I'm actually talking to the GHC/Cabal devs to break that dependency, so hopefully the next GHC version (after 7.8) won't have that issue. Then cabal uses a setup config file with its version written in it, which means the Cabal API version and the cabal-install version MUST match.
Projects not building and scion-browser not working is NOT normal behavior, of course. There are ways to turn on full logging to see in the Eclipse console what's happening.
Scion-browser is slow the first time because it downloads a lot of information, especially if you get everything from Hackage, but after that it's much faster since it only processes upgrades.
When you build a project with EclipseFP, under the scenes it still run "cabal build" on your project folder, so anything that builds via Cabal can be supported. But no, there is no explicit support for Makefiles. I wonder if the CPP plugins for Eclipse would have Makefile support you could use? It's true EclipseFP is targeting Cabalized projects, and you're the first one to request Makefile support.
Thanks for your final kind words. I know EclipseFP is never going the only and true environment to write Haskell in, but I hope to provide a viable alternative and healthy competition to the other solutions.