Should I use a custom taxonomy or custom field..

I’ve created a custom post type, “Reviews”, for a video games site.

I’m in a bit of a conundrum as to whether to include some of the fields as custom fields or custom taxonomies. These fields are “Publisher”, “Developer”, and “Platform”.

In general, my understanding is that you use taxonomies for sorting and things you want to query on, and fields for things where you’re actually interested in what the data is. In this case, I want to do both.

For instance let’s say that the Platform of a game is “Xbox 360”. I want the user to be able to sort by xbox 360 and see all xbox 360 reviews. Additionally, I also am going to want to do a calculation where I, for instance, return the the average score of all Xbox 360 games.

So should “Platform” be a custom field for my “Reviews” custom type or should it be a custom taxonomy for it? If I make it a taxonomy, could I still query on it to return the average score (score will definitely be a field) for all games with the Xbox 360 taxonomy?

If I do it one way and don’t like it, is there a way to go back and change it or would it have to be done by hand?