Some of my need such as 3D rendering will likely never be met by the iPad hardware while 3D modelling would. However, I benchedmarked video export from keynote and surprisingly, the export was quicker on my iPad 1 Pro Gen than on an 8-core mac pro!
My biggest concern is not be able to open two instances of the same app. The workarounds in each app such a PDF expert and notability is different and it would be far easier with as system wide approach. Marking text could be much easier as well: Imaging the two finger curser to move to desired text, drop a third finger and drag to make a selection. The two fingers to cursor could be systemwide as well and not only when the keyboard is up making it easier to select other things such as files, pixels in images or whatever else. What is also irritating is navigating in text without and arrow keys. Make these in the software keyboard.
No need to be offensive or superior over iPad users as it makes the debate climate bad. I am certainly not a kid and I am an academic at at university which indicate quite strongly that I have some academic ambitions. I use an iPad every day for note taking, giving lectures, reading and annotating theses, making keynote presentation, travelling etc because it is more convenient and rapid to use compared to using my mac. An arrogant poster would claim that this is not "real work" as it is mostly consumption of material produced by others.