@DJ Vintage: Thank you very much for the thorough answer!
For my part, it doesn’t really matter if the software is on an iPad or a laptop – isn’t DJay Pro the same thing on the different devices? I already have Djay 2 on an iPad – I’ll take that into consideration as well (and your point concerning the camera kit necessity). Haven’t thought much about the differences between Djay 2 and Djay Pro – one should think that Pro (money aside) would be the ‘better’/future proof choice.
I’ll have a look at the other controllers you’ve mentioned – thought I’m still leaning towards the MTP3, with the extra cost of DJay Pro (for the Mac) taken into account.
How I hate being spoiled for choice! 🙂