backwards compatibility will introduce an emulator for the one. in other words, youll basically be playing 360 on the one. if you stick to the 360 destiny disk, youll be playing on 360 servers and wont be playing with guys on the one. either way, you wont be restarting progress. id say, go with the one, but look into picking up the xbox one version of your games if you want to play with people on the one servers.