I'm a new (6 week) user of MFP. The units on foods are the most horrendous, dreadful mess imaginable. Sometimes ounces, sometimes pounds, sometimes g, sometimes kg. Sometimes volume measurements for things that are weighed. Sometimes weight measurements for things that are measured in volume (liquids). Sometimes I'll see "100 g" but no "1 g." The most troublesome is seeing volume measures such as fluid ounces for dry foods that are weighed. There is NO consistency between similar foods.
I use a digital kitchen scale to weigh most all foods. Fortunately, it can provide both ounces (wt) and grams. But it is REALLY frustrating when a food only has a volume measure and should have a weight measure.
Equally bad is sometimes a food will have ten or more units of measure, but the next food has only one. It's frustrating that end-users can only enter a single unit of measure.
I appreciate you have millions of foods in your database and fixing this would be a huge problem, but is a major user aggravation. MFP should assemble a team of summer interns and have them get this whipped into shape. And be sure to have somebody with common sense driving the project, somebody who knows the difference between weight and volume measurements and when to apply them.