I'm not sure about an iPad not being able to replace a laptop. I use my iPad mini for about 95% of my computing needs. There is one program I use that I don't have access to on my iPad, but I use it very rarely and it's not something that's necessary. Last semester one of my online classes didn't play nicely with my iPad so I wound up using the laptop for that, but for everything else, I pretty much use my iPad. I have a subscription to Office 365 so I have access to all of my documents and spreadsheets on my iPad.
And I have never regretted giving up my full sized iPad for the iPad mini. For me, bigger isn't always better.