Because you already own the cdj 2000 nexus I say go with the djm 900 nexus. Because you get the best of both worlds in terms of functionality especially for home use. You can always use your djm 900 as a midi if you where to use traktor straight through without any need of an extra sound card or serato if you have the sound card that comes with it. Also you can plug a usb, Hd or use cds and play from there with out a need for a laptop. You would also benefit from utilizing the quantize feature when you anaylize your tracks through rekordbox meaning all your tracks would be spot on as far as being on beat when using effects, hot cues, syncing ect...
The only real feature that the T1 has over a set up of nexus's is that all the buttons are deticated for traktor use. But like I said you can set up the 900 nexus to midi control both serato and traktor to your liking and still be able to use your mixer funtions.
