I consider it a step down myself, the pistol does FAR more damage, and you can also put a full auto mod into it. Turning it into a smg.It's the higher tier weapon for AGI if i remember. As it also uses 9mm ammo, just like the pistol, it's just a step up. Not to mention they strengthened the gun if i recall the talks about it.
Similarly, you have a hunting rifle, m60 and ak47 using the long rounds (7.65?), with the last two being guns with more of an auto shoot, than single. Similarly like SMG compared to Pistol.