I'm just asking for a flamewar on this one, but after reading the research that has been done on the much-maligned food additive monosodium glutamate, I see no reason that I shouldn't use it in some of my own dishes.
The facts are that it's a synthetic form of a naturally-occuring substance, and its natural equivalents are still used in food under names like "Yeast extract", "Kelp (or seaweed) extract", and "hydrolized soy protein." Chemically speaking, the main ingredient is the same, but these food additives are incredibly common and receive little (if any) bad press. Since they are chemically identical to MSG, it doesn't stand to reason that the natural version would be safe while the synthetic version would not--in fact, if anything the synthetic should be safer as the material has fewer impurities and is standardized to a certain concentration (as the "natural" forms can vary wildly).
Since I want to cut down on my sodium (MSG has 1/3 the sodium of salt), I think it may be worth running a few experiments. Maybe when I make a few jars of spaghetti sauce this weekend, I can do a batch using a half-and-half MSG-to-salt ratio and do the other batch with plain salt as a control.
I'll let you all know how (or if) this works out for me.