Recent mechanical engineering grad here, I use my (new model) 35s on a daily basis. Despite being somewhat cheaply built (&#x27;5&#x27; button broke early, still works but now wiggles around), I couldn&#x27;t do without physical buttons and especially RPN. I&#x27;m also a heavy user of python for data crunching, but they&#x27;re just different tools for different jobs.<p>Now, that DM-15L is tempting. Bit expensive, but tempting. A boss of mine, during a co-op internship, still had an original 15c on his desk and banged on it daily. Great engineer.<p>As a last aside, for a terminal RPN calc app, my favorite has been &#x27;orpie&#x27; for a while, check it out, I think it&#x27;s built in Ocaml too, which should satisfy HN FP-fetishists.