I was in a very similar situation to you. I had a 13" MacBook Pro from 2010 and an iPad Mini 2. My original plan was to replace the iPad Mini 2 with an iPad Mini 4 and to upgrade to the new 12" MacBook. But when I saw the iPad Pro 12.9" in the Apple Store, I was really impressed and decided to try it out to see if it could replace both the MacBook and the iPad Mini 2.
For the first couple of months, I agonized over whether I had made the right decision. I also kept trying different cases on the iPad Pro to see if different cases and/or stands would help me be more productive on it. I kept my old MacBook Pro just in case, but found myself going back to it quite often when I needed to do serious work.
Then I finally gave in and decided to try out the Apple Smart Keyboard. All I can say is this accessory totally changed the iPad Pro for me. Currently I'm not using any kind of case with the iPad Pro, but I have it docked on the Smart Keyboard most of the time at my desk, and I haven't even used my MacBook Pro in almost a month. I have decided that I'm going to sell it as I no longer need it.
So I would recommend trying the Smart Keyboard. Even instead of other keyboards. Because of the way the screen sits so close to the keyboard, it makes touching the screen easy and not tiring like I would have imagined it would be. I actually find I prefer using the iPad Pro in "laptop" mode docked on the keyboard than in my hands like a normal tablet, and I have grown used to using all of the keyboard shortcuts. As for typing, I find the Smart Keyboard to be just as comfortable as the keyboard on my MacBook Pro. I suppose if you like to use it while on your lap, then it could be a bit more difficult. But when using on a table or desk, it works wonderfully.