Here's another experience report: I ported a small 1 KLOC PHP project to Go this week (in some spare time between large C++ compile times). The primary goal was to reduce the number of supported languages we use.

The port happened in the mechanical line-by-line way, copying each PHP file to a *.go and fixing all the syntax. The project was small enough that automation wasn't interesting.

I agree with the "1/3 time spent debugging the result". Another complicated facet was the lack of insertion-order preserving maps, that PHP applications end up relying on heavily. The error/exception impedance mismatch was not a problem in practice at all.

According to cloc, the original PHP project (excluding vendor) is 1.0 KLOC, the resulting Go application is 1.2 KLOC. I imagined Go would have been more verbose than this, but actually most lines remained 1:1 conversions, and the Go standard library happened to cover a lot of small utility functions that had to be separately written in PHP (e.g. for string suffix matching).

Another interesting point is the number of comment lines in cloc appeared to drop dramatically, since real type annotations are much less verbose than PHPDoc.