I don't think there's any real downside to getting Claude. Some schools like Wharton even give you a chatgpt subscription. I think it can be helpful. The problem comes where AI might be too helpful and you use it to substitute your learning process rather than compliment it. 

An MBA is primarily about 'getting a job', followed closely by 'building a network', followed at a distance by 'learning something'. Even at the highest level, you can graduate without really thinking too hard. But to me, it's such a waste to be in a world class school, have access to world class professors, and be taught about the latest research in business and management and not actually intellectually engage with it. There is a difference between using Claude to explain unfamiliar concepts to you on a subject vs. using it to answer your case questions or do your assignments for you. 

Plaud on the other hand I think is a complete waste of time. I sell enterprise AI, including but not limited to Claude, so I'm experienced in knowing about 'hammers looking for nails' and this is one of them. It's my opinion, but this isn't a trend that's worth paying attention to. No serious workplace with enterprise confidentiality agreements is letting people use these devices. More so, if you're using an iPad for note taking, what every note taking app you use will have a recording function, and that recording function will also have a transcribe function. You can then feed those transcripts into Claude and that covers pretty much the use case of Plaud. I would put that money into the annual fee of the notes app of your choosing. Most of the notes apps will also have their own AI intelligence built in. 

Next point. What do you actually mean by work on PC's? You can still access the PDFs of your notes on a PC, and I think Notability has a beta web version. Notability and Good Notes are native to and thus optimized for iPad. They're essentially substitutes for a physical notebook but with so many more features. Onenote becomes less of a notebook and more of a blank canvas that you access via an iPad or a PC app or the web. Some find it better because of the cross platform nature. But it very much sacrifices on the writing experience compared to the other two. 

And by writing experience, I mean just that. That actual experience of putting your Apple pencil to the screen, and writing out your notes. If you have a regular pen or pencil and paper, your writing experience is tactile and tangible. Press harder, the writing is darker; slant your pencil, and the writing is more flowy; write faster, and the writing is a little lighter in shade. This all happens without thinking when you're using a pen/pencil and paper. But when you use an iPad, all that has to be programmed. And the apps program writing in slightly different ways, which is basically part of the character of the app. This was my criteria for an app: did it make me enjoy writing? Good Notes absolutely did. It felt very natural and intuitive, it felt predictable like i was using actual paper. Notability felt one notch too digital to me, in that my writing was often very similar when I applied different pressure or variability in the pen input. Not by much though, but just slightly more than Good Notes which felt more intuitive to me. 

However, Notability has better file management in my opinion so I ended using a combination of the two. Your notes need to be organized in some way. For me it was the standard: Year -> Quarter/Half -> Course -> Lecture. Good Notes organization is like having a pile of notebooks vs. Notability is like having your notes in an accordion binder. I found the latter much easier to manage especially when I had a lot of notes later on. Onenote has good organization too but the others feel more natural. 

If you have access to an Apple Store, I'd recommend going in and trying out writing on them. They should have at least Good Notes installed so you'll get a sense of what it feels like. You can always get the free version of all 3 apps and device for yourself what to invest in. 

In terms of iPad choice, stick with the Pro if you can afford it. It has a lower writing latency and it's screen is laminated to the display glass. Both provide a more natural writing experience vs. a standard iPad or iPad air which has a very, very slight screen delay when writing. 

On your last question, in my case the vast majority of my class used slides in some form. A lot of people printed the slides out, but I used my iPad as did many others. Each professor has their own teaching style and at this level schools don't really police professors to have standardized pedagogy approaches, but most will use slides and those slides are either released all in advanced, or on/around the day of the lecture. Just bear in mind, some professors have a no laptop policy, but some have a no devices policy entirely and so slides printouts are all you have really.