Following the instructions in their repo (and moving the checkpoints/ and resources/ folder into the "nested" openvoice subfolder), I managed to get the Gradio demo running. Simple enough.
It appears to be quicker than XTTS2 on my machine (RTX 3090), and utilizes approximately 1.5GB of VRAM. The Gradio demo is limited to 200 characters, perhaps for resource usage concerns, but it seems to run at around 8x realtime (8 seconds of speech for about 1 second of processing time.)
EDIT: patched the Gradio demo for longer text; it's way faster than that. One minute of speech only took ~4 seconds to render. Default voice sample, reading this very comment: https://voca.ro/18JIHDs4vI1v I had to write out acronyms -- XTTS2 to "ex tee tee ess two", for example.
The voice clarity is better than XTTS2, too, but the speech can sound a bit stilted and, well, robotic/TTS-esque compared to it. The cloning consistency is definitely a step above XTTS2 in my experience -- XTTS2 would sometimes have random pitch shifts or plosives/babble in the middle of speech.