Query about transferring an account on new Xbox One and Forza player progress data etc

Currently own an Xbox One with Horizon 2 with two player accounts. Would like to play against the other player whilst online.

If i purchase another Xbox One with Horizon 2 is it possible to transfer one of the player accounts from older Xbox One to the new one without loosing player data?

Yes. Mind you, you will need an additional Xbox Live subscription for whichever profile will not have a membership applied as Xbox Gold subscriptions can only be shared when both profiles are on the same console.