I'm surprised Duragloss TMD #253 doesn't get more love.
If you like a nice flat/matte black finish (not shiny/oily), then DG TMD is the ticket.
Has nice durability (2-3 weeks depending on conditions) and doesn't sling. Also, it has a cumulative effect and tends to look better and last...
I measure using a plastic measuring cup with ounce measurements.
For the reasons Al-53 mentioned above - I want to make sure that I have the proper dilution ratio and it's just too easy to mess up and make an over-concentrated wash if you are eyeballing with highly concentrated soap.