I thought it was only up to 10 kts? I wouldn't be too happy departing with a tailwind in excess of 20kts.
I think you'll find the FCOM might say "in a tailwind or in a crosswind in excess of 20kts" - they just forgot the comma after tailwind. Meaning you do this in ANY tailwind, AND in crosswinds exceeding 20kts. I don't think you can takeoff in tailwinds of greater than 10 in the bus. Have just started though, so could be wrong.
Why don't companies understand the importance of punctuation?
The answer to your question, I personally believe it does make a difference, and does stop the nose coming up excessively on the t/o roll. It also allows for better directional control as you roll down the rwy. So though it sounds a little stupid, I think it's quite effective.
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