Hi,
I think it's not only the size.
Maybe it's the power/size ratio.
With the 48 series you can do much more things,
graphical evaluations, etc.
But in my experience many people just need a four-banger,
and very few people really *need* the graphical and symbolic capabilities of the 48 series.
Don't get me wrong. I love my 48GX, and I've written many programs for it in the last (more than) 11 years (search hpcalc.org for 'Hellstern'),
but for daily work as a pro-programmer I prefer my 15C,
because it is even smaller than my 42S, has a better display, more functions than I need, and the batteries last for nearly ten years.
Ok, the display of a 15C is numeric only, but it is ways better readable than the display of the 42S and the 48 series.
There exist at least 2 'emulators' for an HP-41 for the HP-48 series.
The one from HrastProgrammer runs a ROM image, so it emulates the CPU.
The other one, which was sold by HP, is more like a HP-41 user interface emulation, and was available on a ROM card for the 48SX.
There exists a version of the libraries for the 48GX,and it's nice to see all 4 levels of the stack (+ LastX),
and the goal was to make it easier to convert former 41 series users to the 48 series, but in the long run it's easier to use the 48 built-in user interface on the 48, and the 41 (or 42S) on real hardware (IMHO;-)
Raymond