It all gets you gig-ready. The transition from controllers to CDJs isn’t all that big frankly. You need some extra prep work, but other than that … 30 minutes on CDJs and it’s like you never knew different. And using the controller for yourself will give you soooo much extra functionality! For example, there are no hot cue buttons on a CDJ900, just to name a little drawback on this 1500 dollar CD player!
Now if you want the feel of high end CDJ/DJM gear and you were willing to come up with close to 2K for a CDJ anyway, then maybe the DDJ-SZ has your name on it.
SO, don’t worry about club gear too much. If you can do your craft on a controller, you will be able to do it on CDJs.
Greetinx.