Well, no. Gonbes is an upscaler with a framebuffer, the OSSC is a line multiplier. With a Gonbes you can play your upscaled 24khz game on any 31khz monitor, like Apocalypse said. However, with an OSSC the monitor has to support whatever line doubled / tripled / quadrupled resolution the OSSC outputs with original PCB refresh rate. It can be a very odd combination.
I think people haven't had much luck getting 24khz to display on their monitors with an OSSC.