OEM +P is fine in ANY Ruger.
Ruger-only loads are fine in most of the Ruger single actions. Just be wary of the New Vaquero (all Vaqueros are "New Model" but there is a Vaquero <OK> and a New Vaquero <not OK>) and the flat top "re-issue" models.
.45 Colt can be loaded to .44 Magnum power or down to .45 AUTO power. Much more versatile than the .429 mag.
How is that more versatile than a 44 Magnum? You can load the 45 Colt up to .44 Magnum in the right guns, but you can shoot 44 Magnum in any 44 Magnum. You can load the 45 Colt down to 45 ACP, which oddly enough is right around the same power as a 44 special which is very easy to load a 44 magnum down to. In fact since the 44 magnum has slightly less case capacity, downloads in it will be generally a little more consistent than they are in the 45 Colt, though probably not enough difference to really be noticed.
All that said, I'm not against the 45 Colt in any way shape or form, it's a great round. But I don't know that it has any advantage over a 44 Magnum in any way, form, or fashion. I guess the 45 could have a slight advantage in meplate size available, but I don't reckon that's a huge advantage in the overall scheme of the two rounds. But, I will acknowledge that it does exist LOL
The best explanation I have seen of the difference is in the link I posted above. The 45 colt loaded to 44mag standard pressures will drive a bullet 2 calibers larger and 20 to 30 grains heavier than the 44 at the same velocities so yes the 45 Colt at +P pressure is more powerful. Difference on game I doubt you will really see, the larger meplate and extra weight does give more energy to the Colt though. Not enough for me to switch to 45 colt when I already have multiple 44 mags and never saw the need for more power for deer or hogs which is what i use them on.
But they don't load it to 44 pressures. They load it to 45 plus p pressures which is still less than 44 mag. The cylinder walls get too thin even in the heavier guns to load more pressure than that safely. So unless you're going to load 45 Colt exclusively in 454 pistols, or custom 5 shot 45 Colt pistols, it really does not outpace a 44 mag. Because you can load specialty s*** in 44 mag in certain pistols that outpaces any of Buffalo bores 45 Colt stuff. Even Buffalo bore loads a monstrous 44 mag load that outpaces anything they load in 45 Colt, but it is only for one or two guns so it's kind of specialty crap.
The point I was originally making is that hot 45 cold and 44 mag are for all intents and purposes equal. I can load either one hotter in certain stuff, but in reality and in factory guns, the best you're going to get is pretty much equal. Both can be downloaded equally well. So there's not a whole lot of difference, in other words the 45 is not way more versatile than the 44 as was stated. The one advantage the 44 does have is that 44 magnum works in every 44 Magnum where 45 Colt loaded hot will blow up some 45 Colt guns.
I would have never brought up 44 had somebody not mentioned that the 45 Colt was "much more versatile than a .429 mag" which is just not true
PS I've loaded for both of these guns so it's not like I'm a newcomer to either one or have no actual experience. They both work fine