I am not sure if they are changing it but the heirloom items all have an ilevel of 1 on the beta at the moment and with the new heroic and normal instance requirements this means that you will find it difficult to enter any of the heroic instances if you are using heirloom gear. The Ilevel may change when cata goes live but i had to dump both the cloak and the headpiece to get my average ilevel high enough (275 in normal instance and as high as 325 in heroic instances)