I can see how this could be translated to RPN could cause someone to
feel like they have a better understanding of what's being calculated.
Conversely, infix notation leaving someone feeling separated from the
calculation and having much less of an understanding of what's being
calculated.
Maybe. I never really saw it that way, but I can see how someone might think that. If you ever watched a skilled account with an adding machine such as in the old days in an H&R Block tax office -- you will notice they move off their eyes from the paper. Their hands are just typing away, entering digits and hitting the add/subtract/equal keys and they never look at the machine until the end. It can almost be mesmerizing. I could be similar that on a TI calculator, but I never could on an HP.
This separation making it more likely that people will have problems
estimating and having any idea if what they're doing makes any sense or not.
For some people, that probably is true. But I'm not sure it generalizes.
Clem