Need for paper & pencil with 48/49/50 calculators

[carey]

I'd like to discuss the extent to which 48/49/50 calculators eliminate the need for paper and pencil in multi-step problem-solving.

In the old but excellent HP video, Learning About the HP 48, William C. Wickes and Nathan Meyers show how, via chaining calculations and using symbolic equation manipulation, the HP 48 reduces the need to use pen and paper in problem-solving.

My questions are whether you think there's a sweet spot for the amount of pen and paper to use in multi-step problem-solving using 48/49/50 calculators or if you find you're able to dispense entirely with pen and paper? My impression, for now :), is dispensing with paper and pencil is doable, though not always desirable, unless a complete calculation history is available.