Yes, I use the PID to get the best temp for a blend. If I have a coffee that's a little acidic I'll increase temp. If it needs a little more brightness/florals I'll decrease temp.
So, if your coffee is a little acidic, you increase the temp. Please explain what and how, as the lever is a huge chunk of metal, and I am interested how you can accurately increase its temp. Where is the temp measured and how is the increase occurring?
If it needs more brightness/ florals (acidity in my language) then you decrease the temp. So at higher temps you are getting a lacklustre coffee, and at lower temps it is acidic. Too many variables that are not clarified, such as depth of roast, type of bean etc, etc.
I am a firm believer in simplicity, and am not convinced a PID is needed on a properly built and designed lever. Temperature stability is more important.
Out of interest, if your last coffee today is perfect, and you leave your grinder at the same setting, what is the result tomorrow morning (using the same coffee as today), when you:
Pull 6 espressos, one after the other, with a reasonable time lag in between for prep etc?
Assume machine has heated up (say 30-40 minutes).
For Example, using the same dose, and grind, pull 6 espressos without any adjustments.
What is the result in each cup, and how much does each pour differ?