Let's be clear, the SAA has a top strap because that's what the Army asked for.
I won't delve into the strength issue because I really don't think it's relevant. Both designs are obviously strong enough for blackpowder and mild smokeless pressures. Note the only stretched Open Tops we see are either brass or 150yrs old.
I have multiples of both and find the Colt pattern sixguns preferable. Their grips are more comfortable. They are more pleasing to look at. They are more natural pointers and I like the way they handle. I like `em fine but don't see myself ever investing in engraving, fancy finishes or ivory for a Remington.
Lets be clear. All romantic nonsense aside, the top strap design was a logical evolution that replaced the first practical cap lock revolver that Pearson designed for Colt in 1836.
The grip on the Colt revolvers may be superior and the nostalgic qualities of them may evoke strong (though irrational IMHO) loyalties, but the top strap design was clearly necessary to eliminate the archaic wedged separate barrel design and to produce a superior product.
The fact that Colt stubbornly retained it for so long simply demonstrates that had no interest in improving his basic design as long as he could continue to trade on his name and reputation and his pistols continued to sell well.
Winchester, to some degree, trod the same tired trail, retaining the weak toggle locking action of the 1855 Volcanic pistol even when their rivals introduced stronger and better rifles.
It was not until it became clear that they could not produce a .45-70 toggle-locking rifle, and that the public wasn't much interested in weaker propietary cartridges that they finally gave in in 1886.
The fact is that even with strength considerations set aside, the top strap designs are far more user-friendly, allowing the shooter to pop out the cylinder for wiping and to deal with fouling.
The Colt of course needing tools to knock out its 1836 wedge every time the shooter wants to remove the cylinder.
The Remington in particular also simplifies a breakdown cleaning, with it only being necessary to remove the grips and trigger guard with 2 screws to access the internal parts. The hammer spring even just slides out. The Colt requires that six screws be removed to dismantle the grip frame and that the hammer spring also be unscrewed just to reach the same point.
Disregarding the romantic nostalgia, Colt Cap & ball revolvers are a pain in the ass for the shooter.
If you like their appearance and their pointability goody for you.
In terms of practical black powder shooting, they remain a poor second choice.