I have just seen the achievement list an there is one in particular that concerns me, on Halo Reach i was never able to upload anything to my file share unless it was someone elses file, but it always said Gamertag is offensive or some pish, an as i have got every achievement on all halos (currently gettin general on Wars) i dont wana miss out 
Were you able to upload in Halo 3 or ODST?
i never tried in halo ODST, and in halo 3 i had like 4 gamertags so im sure i did at some points, but on Reach as soon as i got the game i was raging i wasnt able to upload some cool -Yoink- lol 
It will probably be different on halo 4 but has anyone ever had this before? Ill go on now an see if its still the same