Beyond that wall of text, a quick note on units. It's interesting (and correct!) that you put "efficiency" in quotes because (at least from an engineering perspective) efficiency is pretty strictly defined to things with equivalent units. You can divide one by the other and measure it as a percentage.

Amount of light you get per watt doesn't quite fit the bill, so we have a closely related measurement called "luminous efficacy."

Units for that are lumens per watt, where lumens are a measure of amount of light (basically watts of EM radiation weighted by the human eye's sensitivity at each wavelength), and watts are the electrical energy consumed per second.

Probably more than you wanted to know, but you never know when that piece of trivia might come in handy.