to be honest I enjoy the iPad Pro experience more than I did my Surface Pro 4 when it came for travel/bed use. I sold my Surface Pro 4 to get the iPad Pro because of that.Same here
I use 12.9 pro and mini for bed too but either can't replace a laptop unfortunately. The pro keyboard is terrible, surfing the web takes twice has long to get to what you are looking for on tablets/phone.
I would tell you to pick up the surface pro 7 or surface go (go to bestbuy it is very small for typing so try it out first) if you already have a Ipad pro. Buying the Pro X would feel too redundant in your use case unless it's replacing your pad pro (this coming from me ).