I would like to mention that Enum.reverse in turn calls :lists.reverse if the first argument (the enumerable) is a List.
With that said, after reading the following in Programming Erlang (2nd edition) by Joe Armstrong, I felt much better about using Enum.reverse with a List as the enumerable:
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If the order matters, then call lists:reverse/1, which is highly optimized.
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Note: Whenever you want to reverse a list, you should call lists:reverse and nothing else. If you look in the source code for the module lists, you’ll find a definition of reverse. However, this definition is simply used for illustration. The compiler, when it finds a call to lists:reverse, calls a more efficient internal version of the function.
So, with a long list, most of the time I’ll always add elements to a list head and then call Enum.reverse at the end and trust that Joe and Erlang have my back. 
But as Joe points out a little later:
The best thing to do is first write your programs as clearly as possible and then, if there are performance problems, measure before making any optimizations.
