jps11920
I am looking to better tailor my practice. Additionally, if one were to do well on medium level questions, roughly what level of performance can they anticipate on exam day?
There is no good way to get an estimate of the final score on the basis of the OG questions. Either the confidence level of the estimate would be low, or the confidence interval would be quite large. The OG is not the tool for scoring. Use the GMATPrep tests for that. At most, you could use the diagnostic test at the beginning of the OG to get a (very) broad idea of your ability level.
I get what you are saying about tailoring your practice though. I'd suggest you use the easy, medium, and hard categories for now, as that categorization is reliable (not so sure about the 200-800 categorization). Finally, there's a lot to be learnt even from the easy questions. Don't ignore them completely.