It works I attempted it last night. I wouldn't doubt that you could get banned. Make a new account to mod it onto then wait a week and see if it gets banned.
yes you can, i modded all my G and it said theres an error at 1st on bunie.net but when i waited a while just mest about on campaign and customs, it eventually said i can unlock recon back (my other account got banned i did it legit)
Agreed it is still out there i modded my gemerscore for ODST,HALO 3 and HALO WARS. Did not get banned and got recon in 2 days after it was done. I can help if you want me to just PM me.