Howdy and welcome!
The 44-40 is a great classic cartridge. It's a great choice. Reloading is a bit more challenging and box ammo is a bit more expensive.
As for the Baretta, despite the transfer bar, it is still the old Colt SAA frame. The Ruger will be more durable and better able to handle hot loads, it's a new design.
As for smooth, that's a matter of opinion, I've got smooth Rugers, smooth Remingtons and smooth Colt replicas. It's just a matter of time, work and some money. The Stampede is new enough that not many are out there, but they are based on the Uberti and share most parts, so they should be very similar.
Keep on asking questions,