OK, regarding the Uberti safeties, there are two. This is the one on the '73's:
When the hammer is pulled back to the first click, the sear, as it protrudes into the safety notch in the hammer, engages a plunger that pivots the hammer block out as seen above. Sort of "semi" automatic, I think. All but infallible as far as I'm concerned, but of course one must remember to pull the hammer back to the first notch. I carry a Uberti almost daily with six rounds, and the hammer in the safety notch. No mishaps yet, but carrying in this manner is a personal choice.
The other safety is used on the open top models and it truly is manual. This safe is in the front of the hammer shank and must be physically folded out. To do so is really quite easy and I find I can engage this safety with my fingernail on either of my open tops.
Safety "off":
Safety "on":
Like Spax, I own a Colt Gen 3 (.44 Special), several Uberti's and two Rugers. They're each unique in their own ways, but my personal preference is for the Uberti's.
Good luck with your decision!