I also write notes on a notepad and scan them on my work computer as pdf document. I'm trying to save the trees!!!!!
by writing on a piece of paper, scanning it, then getting rid of it? haha but i am going through a similar dilemma trying to choose if i need a mbp if i get an ipad. i am starting to think i am just going to get the ipad for now, even though i really want an osx machine. you wont be able to write a paper on your ipad outright, you will at least need a external keyboard to do it. When i had my wifi, i did try to write an entire paper on it. Then i did one once i got back to my laptop, and it is much easier. Multitasking is a MUST. i get a pdf telling me the requirements, open up pages to start it, forget what the second section must be, have to shut down the app, go open up goodreader, remember what exactly it said, go back to pages, keep writing, shut it down, get a source on the internet, go back to pages. It ends up being a much larger hassle than it needs to be. However, as an editing device it would be great.
Right now, you need a laptop. I have a windows 7 machine that works great, i just want to have a full apple ecosystem to take advantage of all the apps that require macs, a better relation between all the products, etc.. But the more i think about, the less i think i would need a laptop for just writing papers or doing powerpoints or online quizzes the ipad doesnt support. But, i could get just a mbp and not worry about any of it. I can afford them both, but it just sucks cause with the 64 gb. 3g and some accessories, its about 1000, and the mb is around 1200. So cutting out 1000 would be nice, but i might go for it anyway.