This is an interesting discussion.

We all want to get the best out of our drugs, be it from levodopa/carbidopa or MP (yes I think of it as a drug) or both. The important thing is to find out in what circumstances L/C is best and when MP is best.

L/C and, more recently, L/C/E have almost always worked well for me. I've never taken MP.

L/C/E has the interesting side-effect that it turns your urine deep orange. So, provided your drug and urination cycles are in sync, you can see if a dose has taken. I find some doses are lost for reasons other than protein competition. I suspect this is due to two reasons:
- delayed gastric emptying, leading to levodopa being destroyed in the stomach;
- constipation stopping absorption in the upper colon.
Does L/C or MP have an advantage here?

What in MP takes on the role of carbidopa in L/C?

John