Something i've noticed with MCC Reach is the Weapon icons on the HUD, and when you get pick up prompt, don't look the same as 360. In fact, it looks like a sort of hybrid of the beta and final versions.

Here is an image comparison.

The weapons also sound more muffled in the MCC and play only one sound, rather than alternate variations, when fired.

Here's a comparison by ODST Brian

Hope these issues can be resolved for the final release.