With the extended battery and bay battery (no slice battery) I was seeing over 14 hours of real world wireless usage (inc. fullscreen video) on my 14" Thinkpad. The Thinkpad is a workhorse, not a toy.
Maybe we don't have the same screens, i.e. there are different models?
Beside, keyboard aren't everything, these laptops are sturdy. Most laptops are flimsy and fail early. I own lots of 2005-2009 models that are impeccable.
Finally, 2nd hand Thinkpads are cheap, You can find a decent one for as much as a raspberrypi2 kit.
I've often thought that the reason I don't have RSSI and shoulder issues (which one can get using a mouse) is that I amp the acceleration (or whatever the term is) up all the way. I use a small mouse (currently a wireless logitech, thanks Doug) and I can move my pointer quickly and precisely across the entire screen while keeping the outside pad of my lower hand (near the wrist) resting on the desk (or couch at the moment). I move the mouse entirely with my fingers, no wrist or shoulder movement at all. If you watched my hand moving the mouse, and took the mouse out from under it, it would like like I was gently scratching the desk/couch.
The downside is that when someone else walks up to my machine to show me something they get vertigo when they first move the mouse.