Convert hook_*_info() hooks to return arrays instead of objects

Early on, I standardized everything defined or returned from a load function in Drupal Commerce to be an object. This was for simplicity's sake - a developer could always trust that the array of checkout panes, a single product type definition, etc. when requested would be returned in a standard form. To do this, I had to use some creative object merging to apply default properties to these objects when loaded:

  $checkout_pages[$page_id] = (object) ((array) $checkout_page + $defaults);

Obviously, if checkout pages were defined as arrays, a simpler solution would've worked:

  $checkout_pages[$page_id] += $defaults;

I wasn't too worried about the complexity, though, as casting objects from arrays like this is possible in PHP for a reason. ; ) However, it can be a little problematic when you have to use odd syntax for things defined in the Commerce modules specifically and not the rest of Drupal. Damien's requested that instead of objects, anything returned by hook_*_info() be represented as an array. This means your major entities, Products, Orders, Line Items, etc. would still be objects, but secondary items like Product Types, Line Item Types, Payment Methods, etc. would be arrays. It will simplify DX in some ways (no casting necessary to merge / iterate over properties) and revert to the complication of Drupal in others (really, it is easier to remember it's always an object). However, it seems like a documentation page could be written that lists every item defined by a hook_*_info() so developers would know when to expect an array vs. an object.

What do you think? If we're to change it, I'd like it to be in one fell swoop so the syntax of the hook_*_info() implementations, the "listing" functions (i.e. commerce_checkout_pages(), commerce_product_types()), and the single loading functions (i.e. commerce_checkout_page_load(), commerce_product_type_load()) is uniform.