Hello! I've almost collected 20 fusion stones for the Ultra Rare (3star) -> Legendary (4star) pet upgrade, but I just noticed that the stats difference may not be worth it?

Here are the stats of what I could find, may not be true but I really need clarification on this!

__________________________________________________ ______________________________________

Macetail (Ultra rare tier 4 pet)

Attack : 1300
Attack boost to knights : 470
Attack boost to knights : 470

_____

Grindhorn (Legendary tier 1 pet)

Attack : 1310
Attack boost to knights : 420
Attack boost to knights : 420
__________________________________________________ ______________________________________

Even though Grindhorn has 10 more attack damage it's significantly worse than Macetail unless the source i've gotten the stats from are wrong, I play on the EU server and upgrading 4 tier 4 macetails into an grindhorn cost 2 million gold and 20 fusion stones so I'm really confused :s

Thanks for reading.