What would you say is the final model that "has it"? Besides my vintage HPs (HP15C, 2xHP16C, HP45) I also have the 50g and the modern 35S. For me, the 50g's lack of a proper ENTER key ruins it. I'm sort of on the lookout for a nice 48 series to replace it for that reason. The 35S at least has a proper ENTER.
> What would you say is the final model that "has it"?
For me, at least, probably the combination of the 48GX and 42S. Both represent the end of the line of HP's traditional hardware engineering, which is such a significant part of using these devices. The software gaps between the 48GX and the later 49 can be made up by installing software into a 48, if that turns out to matter for you.
One of the more significant new parts of the 49 software is the "Meta Kernel", which was externally developed by Jean-Yves Avenard as a 48 extension. IIRC, Avenard ultimately wound up working for HP on their calculators, which I believe is how MetaKernal wound up as part of the core 49G ROM. IIRC, this was also a bit of a reconstitution of HP's calculator engineering effort, as the previous team had been disbanded a few years prior. (ie; William Wickes, who was heavily involved in the 41 and 28/48, wound up at some point working on video conferencing systems for HP.)
The reason I'm also including the 42S is that it's a lot more traditional in the way that it operates. If the 28/48/49/50 series feels like a small handheld computer with a custom programming language, the 42 feels more like an actual calculator (with a lot of capabilities).
