I have not yet had a chance to examine a Uberti with the retractable firing pin, but my experience years ago with a Uberti Cattleman with the tilting hammer block has soured me on the entire concept. I will not purchase any revolver, no matter who makes it, with any such similar system.
I bought my old Uberti Cattleman just as a range toy, and so from the time I bought it to the time I junked it it probably had maybe 200 rounds through it at the most. What I noticed first was that the cylinder bolt started cutting a drag line on the cylinder - the bolt wasn't retracting all of the way - until it finally reached the point that the cylinder could not be rotated at all - either by half-cocking it as if to load it, or by trying to cock it to fire it. I put it aside while I pondered what to do with it. (It was several years old by then and out of warranty.)
Finally one day I decided to take it apart to see if I could diagnose what was wrong with it. What I found was that the bolt cam on the hammer was worn down by the bolt leg, and that the cam was actually cast as part of the hammer - not replaceable as would be on a Colt. This indicated to me that the hammer was made from insufficiently hard steel and/or was not properly hardened. Why was this so? Because the tilting hammer safety block built into the hammer required that there be drilled a very small diameter hole, bottom to top of the hammer, for the insertion of the push rod that operated the hammer safety. Drilling such a long small-diameter hole through a properly hard hammer would be very likely to result in numerous broken drill bits, and generate ruined hammers and bits. Uberti's solution was to simply make soft hammers!
It appears from pictures and descriptions on the web that the retractable firing pin on the new Ubertis require a similar actuating rod with a similar long small-diameter hole drilled through the hammer, just like my old Cattleman.
So, this falls into the category of "Fool me once, shame on you. Fool me twice, shame on me".
If you want a FOOLPROOF SAFE, and RELIABLE single action revolver, then buy a Ruger. The modern Ruger does not require taking the hammer to half-cock to load it - just opening the loading gate retracts the cylinder bolt - so if you don't have to half-cock it, you don't have to to take the hammer to full-cock and then lower it while pulling the trigger. As lawyer-proof as you can get. And this advice is coming from someone who is more interested in the historical accuracy aspect of these guns that with the CAS game.
I have two "original-style" single actions. A several year old Uberti/Cimarron "old model" (with the base pin retained by a screw) in .45LC, and a new Pietta/Great Western II in .38 Special/.357 Magnum. Both have the original Colt-style actions, and I carry them, and practice with them, with the hammer down on an empty chamber.
I also have a "modern-style" EAA Bounty Hunter in .22LR/.22 Magnum that is equipped with a transfer bar. After shooting it and examining its mechanical operation, I really don't see any advantage to the transfer bar operating system. Yes, once you SUCCESSFULLY lower the hammer down on a loaded chamber then the revolver can indeed be safely carried with all six chambers loaded. The fly in the ointment is how you lower the hammer down on that loaded chamber, because if the hammer slips from under your thumb, and you have the trigger pulled - which raises the transfer bar - then the revolver will still fire that round.
I always load the Bounty Hunter with a empty chamber under the hammer.
Outside of a modern Ruger, I much prefer the original action, as there is no mechanical "crutch" that lulls you into sloppy gun handling.