Q:

Can I use "the %whatever% one" and particularly "the other one" in IELTS Academic writing?

From some source I have heard that the other one is informal.
I am considering using this word in the IELTS Academic writing, particularly in the following sentence.  

Overall, both sites offer almost equal extent of accessibility from a city centre, although each of them has its own advantages over the other one.  

Is this appropriate to use these structures in this type of an essay?  
Research conducted before asking:
1. A Google search ("the other one" formal, "the other one" informal, what is informal in ielts essay) gave no relevant answers.
2. SkELL's British corpus has entries of structures "the %word% one".

A:

When making a choice or distinction between two items, we can use the other one to refer to the item that is not being presented to us at the moment or that is not under consideration at the moment.  

Would you like to hear that song?
  --No, I want to hear the other one.
  What other one?
  --The one you mentioned a minute ago, about the walrus.
Do you like this car?
  -- No, I like the other one better.

As the examples show, the phrase relies upon speaker and listener being in sync with one another; "the other one" means "not this one but another which we were speaking about a moment ago. or another that I am looking at and nodding towards right this moment".
Insofar as it relies upon a conversational context, and possibly upon body language, the construction is ill-suited to writing that is not conversational in nature.
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