Eh, difference is that PRC is about 60 times bigger than ROC. Likewise, Singapore is just as successful if not more so than Taiwan. Should China follow Singapore model exactly as well?
Can democracy work in China, probably, once majority of Chinese are educated middle class. But at end of the day, current system, as imperfect as it is, seems to work okay for now. The risk is to end up like India (or worse like Russia in the 90s when it basically imploded), which is world's largest democracy, and given its economy, development, size, and history makes much better comparison to China than Taiwan.