Hi!
I'm a professional DJ and I've been playing for a living 8 years now and I must say that I really like this consept!

I have some suggestions however:

I'd ditch the album art from this layout. Ideally this should be usable without a stylys so make room and strip all the unnecessary components.

I don't think that this device will be able to handle any effects nor mastertempo. I'd initially leave them out - at least until the code is properly optimised.

I'd make the loopdivider (or whatever it's called) arrow-buttons bigger so they'd be more finger-friendly.

I'd also like to see a button that toggles between loop and hotcue buttons.

One thing that I hate about traktor (from whitch most of these elements are borrowed from) is the time only shows time left and not time played. Maybe you could toggle it by touching?

Crossfader should be a bit wider to prevent you from accidentaly touching the track while trying to crossfade.

With the eq's I'd design the interface, so that when you touch the knob there'd like an invisible lever to the knob so you can adjust it with a bigger move. (damn this is hard to explain)

The decks need gain-knob aswell.

What are the eject-buttons for? I assume that they are for accessing the music library?
It's nice touch to put separate 'libraries' for each deck to prevent accidental loading over playing track. Background of these individual libraries should be in their respective colors aswell.
I'd like it to prompt before loading next track if there one currently playing. Or make it so that it loads next track when you stop the deck.

If you intend to use bt-headphones to monitor mixing I'd suggest that you put a separate volume and master-plf fader/knob for them.

Oh and I'd implement a method to adjust pitch-slider accurately by touching either side of the fader (above & below) so it starts slowly moving. It's the same method that is used with serato scratchlive's internal mode...

and I allmost forgot:
pitch-bend buttons! Necessities!

This is my two cents. I'll be lookin closely how this project turns out Good luck!