For me the 48 works better than a 19 for my needs. It is thinner and lighter while still giving the same sight radius,barrel length thus ballistics and with the Shield S 15 mags the same exact capacity. All this in a package that allows me to reach and use the slide catch and magazine button more easily and without changing my grip so my reloads with a 43X/48 are the fastest and most consistently smooth as any other gun I have shot. When it comes to comparing or choosing the 48 over a 43X it gets real tough for me as the 43X has all the grip benefits and I shoot it as well as the 48. I also like how the slide cycles on the 43X as it seems to return nicer to point of aim where the 48 seems to recoil less and with less muzzle rise but slower. I really wish Glock would use a full length RSA as I believe that would make it about perfect and improve it for recoil/response feel.
In the end I am using a Sig 365 most of the time and looking for a 365XL since I think it splits the difference between 43X and 48 almost perfectly while using a longer RSA and appearing to have less issues with reliability,striker and primer drag than the 365 had early on.