I am going to go for it as a laptop replacement for professional use, and have the SG 10.5" 512GB LTE For me that means financial and accounting consulting, as well as running a motor racing team and its website. Lots of web-based accounting and finance software, lots of Keynote presentations and complicated Numbers and Excel files to manage, wage slips in PDF, scanning in and manipulating invoices and receipts also in PDF or image formats. Also creating literary, photo, and video content for blogging, Youtube, and Social Media purposes.
I have already long since completely replaced my personal laptop with an iPad, since the iPad 2 in 2011. Now seems like the first time it may be feasible to replace my professional laptop as well (what that means for me, anyways).
I do have a 27" iMac that I will be continuing to use with Final Cut Pro for video editing, and I don't intend to ever replace a desktop workstation with the iPad. That's not what this is about. This is about replacing a laptop.
If Files.app in conjunction with drag and drop works in iOS just like it does in macOS I think we might have a winner.
I will probably keep my mini 4 as my "personal" device, and use the 10.5" Pro as a directly professional replacement for my rMB.