This dress is a win-win for you because you look stunning in it at both lengths. The original length on you looks as if it's meant to be worn at that length, whereas the model looks like she's making do with an above-ankle length because the dress is too short for her (spoken as another tallish person).
The two-tier version also works -- in fact you look amazing in it. Rarely can layered tiers look so perfect in both iterations.
So my suggestion is to wear it as a maxi, for fun and novelty, until you get bored with it, then give it the chop knowing it will still look super. (I chopped off a tiered maxi sun dress remotely and the chopped version rarely got any wear.)
Btw summer maxis are great in air conditioning.