If they had something better than OpenAI's Advanced Voice Mode and it came with unlimited access I'd consider it. If Advanced Voice Mode was just 15% better than it is now, I'd find $200 a month to give to OpenAI for unlimited access.
I believe it's partly due to it doing Whisper processing remotely (correct me if I'm wrong), which introduces lag and slows things down.
Gemini does voice processing locally through text-to-speech and voice conversations with Gemini are soo much smoother.
The downside is Gemini does much more poorly than ChatGPT at uncommon words and when I code switch between languages. ChatGPT is just excellent at understanding uncommon words and in different languages.