I bought my first HP when the 41 was introduced. I learned the RPN principle in two minutes, and have been convinced about it ever since. I have been using a 48SX since that one came on the market, with much pleasure (great manuals). I was, however, surprised to find that a friend of mine, a now retired professor at a major American university was violently against RPN: "It is a stupid and illogical system. I discourage my students from using it!"
I don't know how much damage he alone has done...
John.
PS. Shortly after I got the 48 I wrote a small program that ought to have been built in: STSM (Stacksum) which will add everything on the stack.
"1 DEPTH 2 - START + NEXT"
This one is very convenient, and I do use it a lot!