Hi John
As you know, I have used laptops for years, both for midi playback and lyrics and notation.

I scanned several thousand lead sheets into the laptop several years ago. I organised them into categories and it worked fairly well as long as I had plenty of time. Aside from the time it took to find and load, I had a problem with fitting the whole score on the screen. I could use the zoom, but then it was too small for 81/2x11 scans to be read. I tried a scroller, but too clunky.

The second advantage of the MPP is that you can write performance notes on the screen and save it.

Thirdly, I use my laptop for playing back midi notation to play over. I can go from that to playing a style with the score right there in MPP.

The appearance of the score is far superior. The ability to press a footswitch, or tap an arrow to immediately turn a page to the same or next song. The ease of carrying a small tablet loaded with six fakebooks.

While these are advantages, it is not to say laptops are not adequate for many. It is that I need every advantage I can get, and this is one them.