I too have been wondering if having a tablet with a stylus would be a useful feature for marking up / digitally writing on PDFs or Powerpoints... For undergrad I just had a conventional non-touch laptop... and honestly I was one of the last few folks that would actually print out those 60 slide PPT lectures and do old school pen and paper notes... I'm thinking printing the lectures for dental school would be insane/horrible though so I've been looking at the 13inch HP Spectre x360 with i7 recently, I like how it is a pretty powerful 2 in 1 and can act as both tablet or laptop...
The surface pro-4 is also a neat device and imo is the mother of all tablets (if you buy a higher spec model), it can also be converted into a pretty regular laptop with the additional $130 keyboard you can (must) buy for it... I hear the clip on keyboard isn't too sturdy if its just in your lap / not on a desk so that's one of the reasons I'm leaning towards the Spectre