Quantisation tradeoff is an interesting question. My experience so far is that larger models with lower bit quantisation seem to perform better than smaller models with higher bit quantisation. So, e.g., 30B-4bit appears to perform better than 13B-8bit. But, then, an 8-bit quantisation seems not really distinguishable from the non-quantised model, so what benefit might you gain from not quantising the model.

Of course, speed, accuracy, power consumption, etc are all considerations, sometimes at odds with each other.