Math determining if you are better off using the coin boosts. Considering average coin boost is ~50%.

In order to recoup the 500 coin loss you should average at least 1000 coins a game (50% of 1000 is 500). Anything you average above 1000 is all gold (literally-ish).

To figure out if you should use the 5>4 you need to determine your average coins pre boost for when 5>4 is and isn't activated. Considering the same 50% coin boost, you need to gain 1200 more coins with 5>4 activated (1200 50% = 1800 to cover the boost). 840 coins more during these sales.

TLDR: 1000 use the coin boost 1200 pre-boost more with 5>4, use 5>4 (840 during sale)