Can I use a DJM T1 to control rekordbox instead of traktor ?

Currently, no, you can't use it to control rekordbox but as @Daniel says, it can be configured as the audio interface. Should rekordbox feature support for additional mixers or MIDI in the future, then yes, you would be able to.

nice question, would be so great to use it on rb!

since you can use it with any soundcard is should be possible to use it in external mode. but since there is no midi mapping ability actual there is no way to map the effect section.

Thanks for your replies.
so there's no way to use the T1 made by pioneer to control the pioneer software? The mind boggles?

I know this thread is quite old but I was googling this same question now that the rekordbox can support DVS and the T1 was listed as a supported mixer and I happen to have one in hand almost getting ready to get rid off.

I test it yesterday and it works great with Rekordbox DVS, once you choose the DJM-T1 on the preferences it will install a driver and everything is mapped except the fader with the video which I think all you have to do is map it yourself with the learning option.

I haven't tested what is mapped or not but so far the effects, the hot cues, the samples, the transport buttons, the Browse and assign deck. quantize toggle between decks.