I have been drinking espresso for many years. I have always read that the temperature range for extraction should be somewhere between 195-205F. Between 198-200F I can't really tell the difference, but at 202F and up is always very bitter with all the flavors muted no matter the blend. Are there any blends that taste best at those very high temperatures? I am just curious since that is part of the temperature range yet I don't know of any espresso blends that should be extracted at those temperatures.

Well I don't really drink blends so I can't answer your question directly. However, I regularly use temperatures around 203-204 with light roasted single origins.

From what I recall, Unicorn Blood by dark matter in Chicago is very lightly roasted and would probably require the 204 range.

Guess it depends on bean/blend and your own taste. I just had a batch of darker and oily then usual blend and had to lower my PID to 199, now I'm on a different blend and it's medium and have my PID at 204 or 205 can't remember lol.

It all depends on the coffee and the roast level. If I am pulling shots of a bright, acid-forward coffee which was roasted primarily for brewing, I usually prefer a hotter extraction temperature, often as high as 205-206F. The zone around 200F usually works better for coffees that are taken into the city-plus to full-city range of roasts, which is my default for a coffee or blend that is being roasted primarily for espresso.

All of this, however, must be adjusted based on taste to suit the specific bean. For example, I am currently pulling shots of a Rwandan bean (described here) that I roasted fairly lightly, with a focus on brewing. But this particular coffee has an unusually savory character, and it ended up working well at a cooler temp (somewhere around 202-03F), as if it had been a darker roast.

It is all in the coffee and roast. Some work better at lower temps while others work better at higher, just like dosing and timing. It varies coffee to coffee.