However, using it would require you to rewrite the init functions of all

SPObjects. ...

Replacing GObject-style initialization with constructor / destructor

shims in the style of NRObject would considerably simplify removing the GObject dependency later and reduce the burden of maintaining the init / dispose functions.

Well, please don't do that, I'm already done removing the GObject dependency, take a look at my branch at https://code.launchpad.net/~engelmarkus/inkscape/cppify .

Regards, Markus