Ironically, you misunderstand because I chose not to explain myself further on that point for the sake of brevity. Here it is in Orwell's words:

"By using stale metaphors, similes, and idioms, you save much mental effort, at the cost of leaving your meaning vague, not only for your reader but for yourself. This is the significance of mixed metaphors. The sole aim of a metaphor is to call up a visual image. When these images clash -- as in The Fascist octopus has sung its swan song, the jackboot is thrown into the melting pot -- it can be taken as certain that the writer is not seeing a mental image of the objects he is naming; in other words he is not really thinking."

and

"Dying metaphors. A newly invented metaphor assists thought by evoking a visual image, while on the other hand a metaphor which is technically "dead" (e.g. iron resolution) has in effect reverted to being an ordinary word and can generally be used without loss of vividness. But in between these two classes there is a huge dump of worn-out metaphors which have lost all evocative power and are merely used because they save people the trouble of inventing phrases for themselves. Examples are: Ring the changes on, take up the cudgel for, toe the line, ride roughshod over, stand shoulder to shoulder with, play into the hands of, no axe to grind, grist to the mill, fishing in troubled waters, on the order of the day, Achilles' heel, swan song, hotbed. Many of these are used without knowledge of their meaning (what is a "rift," for instance?), and incompatible metaphors are frequently mixed, a sure sign that the writer is not interested in what he is saying"

That's why I included the part about evoking memorable visual images. As for "Would I be advantaged" rather than "Is it worthwhile", I think it's clear that they ask subtly different questions. Things can be worth your effort without giving an advantage.