Don't know what your research was, but I seriously doubt that the FAs action is any stronger than that of the X-Frame. The X-Frame also was never intended to replace the Mountain Gun or it's original purpose. It's intention and purpose is to be an accurate and effective deer hunting handgun out past 100 yards. The short barreled versions intended for SD came out afterwards as folks created the demand for them. As for SA vs DA, most of us have a preference to the grip angles associated with both. I don't own any SAs anymore......not because they are not good guns, but because I prefer the grip angle and actions of DAs. But them I prefer bolts over semis in a rifle and SxSs over pumps/autos in shotguns.
That said, the OP asked for responses from folks with actual experience and not opinions from folks that have never shot one or shot one once. IMHO, there is no other revolver out there that has the accuracy of a long-piped X-Frame or is as pleasant to shoot with legitimate .460 loads. This comes not only from my experience of shooting thousands of rounds thru mine, but by allowing others to shoot mine. It has always amazed me how accurate first time shooters are with this firearm. I generally shoot my hunting revolvers @ 70 yards and the reactive target I use is a bowling pin. Even first timers have no problem hitting the bowling pin when using a rest. I have watched experienced handgun shooters taken to school with their Ruger and FA .454s by first time shooters with my X-Frame. There relly is no comparison when it comes to accuracy.
That said, the .460 is a handloaders cartridge. They are very expensive to feed, even with hadloaded ammo. If one cannot afford to feed them, they should stick with a .44 mag. But,at the range they are just as comfortable to shoot as a long-piped .44 and much more pleasant than a FA or Ruger .454. Basically because of the weight and fit of the handgun. While many wine about the heft of the .460, any time you shoot a handgun at a living target past 50 yards, you need to use some kind of rest. Once you use a rest, weight is a moot point compared to accuracy. As for barrel lenght, it depends on the usage. If it's only for protection from Dangerous game, then a short barreled revolver is all you need, but if it's going to be a primary hunting weapon for deer sized game and larger, I suggest a 8'' or longer. I have the 10.5'' PC model with the built in comp and have never regretted getting it.