I develop with Eclipse and MDD at my day job, Go in my side projects. I'll definitely evaluate Extend for the day job enterprisey stuff, but in Go, I don't miss the class hierarchy at all; I find it very refreshing.
Go is cool. Go isn't too fast and doesn't have as much tool support as Java/Xtend. Go may be great if you're doing network programming on Linux. Like many tools originating from Unix environments, the cross-platform support may not be a top priority.
Go's cross-platform portability is quite good, writing portable Go code is infinitely easier than writing portable C or C++ code, and probably as easy or more than Java.
You're set as you already use Eclipse. :-)