u can use them with software, and u 4 deck mix with them (how often will u do that?), and you will have much more as the cdj400 has 3 effects, a djm400 has a minimum of 8 effects, + traktors effects.... im not trying to flame u sol, just trying to help, but your creating advantages that arent there...i think your thinking about it the wrong way, here is how i see it Its more expensive then The CDJ's and mixer its based on Why would you buy something that only "based" on another product when your could buy that product for less it will have more effects which you say you want it can do everything the DDJ can with the software Then it can do it all again without the software, the DDJ cant You say you want to be in the club 1 day, CDJ's are the club standard you say its all built into 1 so you obviously want portability...i just measured my CDJ400's and mixer in there roadcase (and thats with a DJM800 12" mixer, DJM400 is much smaller) and it was an extra 15cm wider then the DDJ, so a tiny bit bigger because of its protection