Hello! Just received the DDJ-SX and played with it over the weekend, and wanted to share my thoughts. Before anyone asks, my firmware and app are all up-to-date. :)

I previously owned the DDJ-S1, and loved it. Before that I had 1210s + vinyl, and then 1210s + Scratch Live, so I'm not new to DJing, digital controllers or the various incarnations of Serato.

First thoughts on the DDJ-SX:

1) The whole things feels better built than the S1. The platters are more solid, the channels have levels. It feels less plasticky and more pro.
2) The platters are too solid! Backspins and beat juggling are nigh-on impossible, you just can't spin them fast enough. Some kind of setting or screw to loosen them would have been great.
3) There are missing features from the S1, and I don't know why they have been removed:
- a) The lights underneath the needle drop band that show you the current position of the track. I miss these.
- b) The vinyl speed knob was great for slowing the stop speed down for big dramatic stops
- c) The ability to hold shift and use the needle drop band to leap through the browser window was great
- d) The raised legs under the unit so that there was room to slide your laptop underneath was a much-touted feature, and great for space-saving. No idea why this was removed. I'm tempted to make some bit of wood to achieve the same thing!
4) The platter is not sensitive enough. On the S1 I could tap my finger repeatedly against the platter to achieve a sort of stuttering sound. Back with my 1210s, I would do the same thing by flicking rapidly between the line and phono settings with a little switch. I was hoping "stutter" would achieve something like this but it doesn't :( Does anyone know a way to get that kind of transform effect?
5) I think the cross-fader and knobs are not user-replacable with alternatives, so still can't use the performance knobs from DJ Tech Tools (www.djtechtools.com) or Innofaders :(
6) When my DDJ-SX arrived, one of the pads was stuck. This meant rolls and slicing completely didn't work. I was panicking that I would have to send it back, but some serious wiggling sorted it out.
7) On the S1, the last loaded deck would automatically be cued to the headphones. Now I have to do this by hand :(
8) I love that I now have a specific pot for the filter, instead of engaging filter junky mode and losing the bass eq knob. It would be amazing if this could be spring loaded somehow - but I might be being optimistic here!
9) Touch sensitive pots like on the new Ableton Push thing would be amazing for highlighting in DJ the setting that you're messing with
10) Slip mode doesn't seem to modify everything that I expect it to. When scratching within a rolled loop for example, the time still seems to go out.
11) A display on the unit itself would be great - showing loaded tracks, current BPM, etc.

On the whole, I love the thing. But there's still lots that could be improved, and I'm at a loss as to why some of the great bits of the S1 were removed.

Thoughts on Serato DJ:

1) It feels very similar to Itch, but buggy too.
2) Sometimes hitting space to move between panel modes doesn't work. Even when pressing the panels button on the SX, often you get kind of lost between modes and unable to get back to where you started.
3) The BPMs keep failing to detect. When I play the track, they are detected but sometimes no grid show up. When the grid shows up sometimes it is wrong, and sometimes even when grids are showing on all tracks, Serato DJ still says they can't be synced :( When restarting DJ, the BPMs often don't persist which is such a pain. And when clicking "analyze files" often DJ thinks all the files are analyzed, even when I know they are not.
4) All of my tracks live in iTunes. Every time I build a crate, and fill it with tracks from my iTunes library - these crates are lost when I restart DJ :( This is super frustrating. In the end, I just made the crates as playlists in iTunes.
5) Often the BPM is detected at half speed (i.e. 88 instead of 176) - this is not a big deal, but it would be great if when ordering by bpm it showed tracks that were at compatible BPMs side by side (i.e. 88 next to 172) rather than making me scroll all the way through.
6) In Itch, tracks would go bright green when they had been played. In DJ, they go grey which is much less obvious. Often, I'll cue up a track and change my mind and load a different one, but it still goes grey. It would be great if there was a setting to only mark tracks in grey if they had actually been played out loud - i.e. played and faded to, rather than just played through the headphones.
7) The autogain doesn't seem to be worth much - it seems that if this is enabled I shouldn't have to mess with the trims at all, but I definitely do.
8) On occasion, the track just went completely mental and played back at like 12 times the normal speed. And I was getting a lot of drop-outs where I wasn't with Itch.
9) Only being able to detect BPM while offline is frustrating.
10) In the offline player, it's easy to make tiny adjustments to loops, but not to cue points - they have to be done by hand. :(
11) Turning the effects on and off makes a horrid sound with a slight delay. It would be nice to be able to turn an effect off and choose to have the effect fade out instead of stop abruptly.
12) Also, when changing BPM (say I'm playing a track at 120 when it's natural speed is 140) is very abrupt and tricky. An option to switch BPM over x amount of bars would be epic. Like, go to natural BPM over 16 bars.

Again, I really like DJ - I love having four decks! But the bugs are really worrying. I've deleted the _Serato_ folder and let it get recreated but this didn't change anything.

Any idea when the next revision of DJ will come out? I'm playing out on Friday, and worrying about whether I should be using it live or not. Or is Itch compatible with the SX, but without four decks?