My son needs a portable Windows device for school next year. The school are recommending Surface Go's and Surface Pro 7's with 128gb RAM. I will probably get him the Pro and I see that you can upgrade storage with a mini SD card. But is this a viable alternative to actually having more built in storage? The 256gb version is quite a jump in price. He would probably use it outside of school too for light games and watching videos (he has a good desktop and an ipad). Thanks.