Depends on what you are doing and what you are comfortable with.
I'm an engineer and when I have to do field work I usually bring a calc (41 or 15c). If I have to make a call, look up data, etc.. I can still run the numbers at the same time. But you are correct in that I prefer an actual keystroke.
In the office I mainly use spreadsheets and use a calc to confirm the numbers.
-Bill
My wishes would be a Swiss Micros Blank Nut where we could flash a variety of firmware (like a 43s) wink, wink.