I did never use a 16C, but I have a 42 at home and use it very often. It goes so far, that I also have the 42 app on my phone as a replacement for the default calculator app. I am using RPN, and I think I'm the only one in my age category that does (at least none of my friends who studied ever heard of RPN) - it's such a superior way to calculate. I usually have problems to work with a "regular" calculator due to being used to it "4, enter, 5, times" instead of "4 times 5".
If this would be a 42, I would definetely buy it. My 42 is a gift from my father and time did not only good to it.
/edit switched UPN to RPN, as I got the translation wrong
You might want to consider iHP48 app, it is my goto phone/tablet calculator running a 48 ROM. My goto desk calculator is the DM42, though I occasionally use my 50g for units or on the iHP48 app instead.
If this would be a 42, I would definetely buy it. My 42 is a gift from my father and time did not only good to it.
/edit switched UPN to RPN, as I got the translation wrong