The PDA model does not matter for the screen's virtual size. As far as I understand (let's say, assuming you are reading the forum on it), you don't want to use reading glasses, so you have to hold a PDA at the arm's length to focus on the screen better, but not perfectly, thus needing to increase the page zoom in order to have a larger recognizable font size, what is clipping the content of the page, thus asking for a physically larger screen to reduce the effect?...

I would rather carry the glasses than suffer like that. They are less than a buck off eBay (I bought 3 pairs once, +1.5, +2, +2.5 in a large Pilot style framing). Great for tinkering with micro electronics and for reading the phone in the bed.