I take always in my travel bag both an HP41CL and a HP Prime. But when it comes to do calculations at work, it is always the HP41CL that I reach for.
On one side, the legibility of the screen is better in our office - there is higher comfort in reading the 34 year old segment screen than the new LCD computer screen.
Second, most calculations are simple enough to be done without resorting to complex functions. It would be totally different if my job involved lot of vector or matrix use - data management is couple of orders of magnitude better with the Prime (as it is the case if it was statistics - data fill in is so much better with it)
Third: programming the HP41CL for simple tasks is so much easy and bug free (at least with my current knowledge level). Once you have finished the program, you can assign it to a key. It can be done too with the Prime - it is just a little bit more cumbersome.
Fourth - it is very easy to set up an alarm with the HP41CL - easier even than setting up your iPhone for the task, as I have the XYZALM function assigned to a key.
The power of the resident calculator there (a Prime prototype, with the white back - these will be collector items in EBay in the future) does not make me forget how easy most tasks are with the 41CL (loaded with the Advantage and Sandmath packs). I guess that I will need to devote much more time to learn the Prime in order to get an even playing field.
It now takes me minutes to make any useful program by using the HP41CL and the additional functions contained in both the Advantage and Sandmath packs. My mind is wired in RPN - which is not necessarily an advantage in these days. It takes me much longer to make a very simple program in Prime; and somehow I manage always to introduce a nasty bug in my first attempt, while most programs in HP41CL RPN work well, first time.
If you always wanted a HP41c and you could not at the time (it was my case), and now you can but you think it’s not worth it anymore, think twice! With a 41CL, you don’t need to buy additional modules and you have an incredibly function-rich calculator, which is still expandable. I bet it is difficult to find a significant scientific application for which there are not programs already recorded in all the modules the HP41CL comes with.
You can find quite cheap HP3468A/B multimetres, that allow you to record measures at will (and, if you have the time module, program readings in specific time periods). You can print the results with either the infrared printer and a new HP 82240B printer, or an old HP IL printer, and then store them in the enormous memory of the 41CL. And it is still supremely portable.
In the future, when these are not available anymore, you will hate yourself for not having the calculator of your youth in the best possible format! Order now when it is still available!