Aren't quantized models different models outright requiring a new evaluation to know the deviation in performance? Or are they "good enough" in that the benefit

Aren't quantized models different models outright requiring a new evaluation to know the deviation in performance? Or are they "good enough" in that the benefits outweigh the deviation? I'm on the fence about whether to spend 5 digits or 4 digits. Do I go the Mac Studio route or GPUs? What are the pros and cons?