Your calculations of the per match benefits are correct, but you once again left out the cosmetics that come with the purchase, so your overall GP comparison is wildly incorrect. No matter how much elite time you buy its never going to get you a single piece of cosmetic gear.
I'm not saying that hero ships are more efficient for grinding than elite time, just that the comparison is not that simple.
Also, the fact that a cosmetic bundle holds its value after you have completed the grind should be taken into account (per match bonus xp/credits dont matter once you've researched and bought everything).