I had a look at the iPad Pro and agree that it's fine for looking at pics, and is fast. But I am not sold on the form factor, although it is not as heavy as I had expected.
Unlike a regular iPad, you cannot hold it in one hand for any length of time, so you'll end up using the detachable keyboard. Trouble is, the Mac-like keyboard has no trackpad, so you end up tapping the screen. The stand is, however, not particularly strong, so the whole thing skitters around. Having 3D Touch on the IPhone but not on the iPad seems odd.
It's great for drawing things, but I would not use it for culling, tagging, annotating my pics on the go. Ingestion is glacial and syncing the results back to home base Lightroom a guddle.
For that task, the Laptop remains the simplest solution, even though it is heavier. The new Surface looks good, but seems to have the sort of glitches that don't seem so prevalent with the more expensive and heavier MacBook Pros.
I have a Pro too. With 4GB of RAM, and a very fast processor, it could theoretically deal with any dSLR Raw files, if software were available.
My 60 year old eyes tell me that the Pro was a good deal. I like it a lot.
As it stands, I am really happy with the Pro as it allows me to read downloaded books, web pages and PDFs without eyestrain, scan through email, and even make written annotations and idea sketches. I don't think one should hope for more.
The iPad is like the original Mac, a machine with a special purpose OS with a complex programming model and "rules" that hobble software creation. As was the case for the Mac, the special-purpose system was commercially useful initially, but is now proving a hindrance in many cases.
As an example, it has a web browser, but it is impossible to use multitasking to run an iPython background kernel properly.
If the multitasking restriction were lifted, one might run a lot of software as faceless apps with browser display and interface.
My feeling increasingly is that someone should bring out a pocket "iPad companion" Linux computer that could be programmed easily, use standard "small format" SSDs, and do the "computer" stuff.
Edmund