Ok so after that little high resolution eye opener about why its time to move on in terms of the two turntable metaphor thing for most folk that aren't really looking to be scratch turntable technicians and just want to be able to beat match tracks whilst mixing seamlessly and progressively, I still have to admit that I still generally prefer something a little more substantial that allows me to do much more for my main rig. But it looks like someone else already informed you in advance with the usual yawnsome Lego analogy.
With my current touch tablets ability to boot up these days being about as reliable as any one persons chances of winning the lottery (slight over exaggeration there but you get the idea) I thought it was time to look into other avenues that would allow me to directly interact with the Ableton interface via direct touch.
I needed something that was reliable and able to perform without suffering from audio drop out whilst using it with my Zero4, something that was realistically portable, and above all wasn't likely to overheat to either crash or blank out from poor thermal heat displacement from bad design. Sure I guess the fact that I'm currently in a warm country with no air conditioning doesn't help but at the same its not really an excuse since I've seen other machines just as capable if not more so operate under these conditions without becoming capable of scalding any part of your protective epidermal layer.
But buying a whole new tablet that was fast enough and didn't seem to suffer from any overheating issues was going to be expensive. Expensive enough that I'd have serious issue with parting with cash I don't even have to begin with. Plus it would have just been far cheaper just to just upgrade my current Precision however it would have lacked the direct touchscreen interactivity I'd become so accustomed to. Plus it just seems a little lame to be trying to DJ in real time by pointing, clicking, dragging and dropping with a mouse.
If only there was some way of using something like the iPad as an extended desktop whilst still being able use its direct multi-touch and pinch'n'zoom gesture control capabilities with any object or interface that was placed on it. Well it looks like someone finally went and did it. It'd certainly be cheaper then buying a whole new tablet PC.
After a little digging around it looks like I finally hit pay dirt. You can now finally use your iPad as an extended desktop for your Mac whilst allowing you to use all the multi-touch and pinch'n'zoom control gesture features of the iPad in order to interact with whatever is placed on the desktop space of the iPad. You just need to look up something called Air Display. It works by connecting and streaming the data between your Mac and iPad over a Wi-Fi connection.
PC user shouldn't fret either as its also apparently XP compatible (32-bit only) too as well as being Vista and Windows 7 compatible too catering to both 32 and 64 bit flavors of the OS.

Related Post: The Korg Zero4 after a couple of years testing

Link to the Air display site: http://avatron.com/apps/air-display/