Wouldn't you have those same problems with an LLVM-based backend? LLVM moves very quickly, and AFAICT upgrades are non-trivial.
The problem wasn't the code generation, it's that it was maintained in a way that made it very difficult to update in distributions. They also broke the stdlib in a few versions. But even if you ignore all of that, if it was supported by upstream then we would have more fate in it than using a franken-compiler. ;)
We (SUSE / openSUSE) had an incredible amount of issues with gccgo. The main problem was that the runtime wasn't updated often enough, they had some odd patches that broke the runtime, and you generally had to update the compiler to update the Go version (quite difficult in enterprise distributions).