Finally switched to the Zagg Rugged Messenger keyboard case after receiving it a week ago.
The keyboard feels great to type on and the backlit keys are very nice, but the trade-off is that the keyboard is thicker and much heavier than the Apple Smart Keyboard. Backlit keys are always useful on flights.
Back cover lacks cut-outs for the speakers so sound is muffled if you watch videos/listen to music.
"Lapability" is great compared to the Smart Keyboard. There are multiple viewing angles when attached to the keyboard, but none that allows you to "stow" the keyboard away - this is an issue if you sometimes consume media or need to use your iPad for a presentation on a small coffee table or stand.
Overall I'm a little underwhelmed. It's great if you use the iPad Pro primarily as a laptop-replacement or for day-to-day business use, but if you use it for media consumption, I think the muffled audio will really get to you. I travel with my iPad pretty often and I usually use it to play podcasts or videos when I'm in my hotel room so that's a huge factor for me. Unless you greatly value a good typing experience, the Smart Keyboard + SwitchEasy Coverbuddy or UAG Metropolis is more versatile combination.
(Edit: Also important to note that the keyboard connects via Bluetooth and not the Smart Connector)