The alloy framed guns were not especially heavy (e.g. 5904 is 4 oz heavier than a G17) and are not especially large guns. They had a rather slick single piece grip that had hilariously flat side "panels" to keep the bulk down more. The "backstrap" was part of the stock unit so you could choose shape and size further. A handful of agencies even issued single stacks (39xx) for some officers, as it's a system. Not available with Beretta or Glock (esp back in the day). Now, I have seen plenty of complaints of size and trigger reach etc with the Beretta, and it was pretty well issued for a bit there at the auto transition time. Heard (much less so) similar complaints with .45/10 Smiths, and the .45 Sigs, at the very beginning with the Glock for being so "blocky" but not really at all for 59-series guns. I even saw a handful of small-handed officers who went back up to the double stack Smith after range staff assumed all girls get small guns, and it turned out they could handle the full size just fine (and: more bullets!).