Anything that has a transfer bar safety can be fully loaded. That includes all Ruger DA revolvers, all SAs from 1973 forward, plus most of the older Ruger SAs has had their free retrofit applied.
Recent Taurus designs have been transfer bar as well. No problem.
Taurus used to use hammer blocks, which are OK but need testing once in a while. The older the Taurus, the less reliable the safety. At a minimum, check to make sure it's working.
S&W now uses transfer bars too. Any post-WW2 hammer-block-based S&W is still OK...an engineering change to their hammer blocks in WW2 was a good thing. I wouldn't street-carry a pre-WW2 S&W.
Most 20th Century DA Colts used hammer blocks of a good design. Always test when purchasing, but otherwise no problem.
TO TEST:
* Unload the gun.
* Check again.
* Cock it.
* With the barrel pointed straight up, drop an unsharpened pencil down the barrel nose-first.
* If you dry-fire the gun with the trigger, the pencil will jump out (driven by the firing pin).
* Next, do the same except finish dropping the hammer without your finger on the trigger. The pencil shouldn't jump.
* Another way to check: with the pencil in there, finger off trigger, move the hammer back and forth a bit...including moderate forward pressure. None of this should transfer any pressure to the pencil.
* Yet another: without a pencil, you can usually look sideways through the empty gun and confirm that there's no firing pin visible even when you push forward on the hammer - yet after a dry-fire, holding the trigger back, you'll see the firing pin. Pull your finger off, you should see the pin retract. Cool.
Any gun that passes these tests should be safe six-up, with the pre-WW2 S&W exception noted. (There's a hammer block, but it can break if the gun is dropped...)