Granted, they are not like Snap-Tights (sp?) as Truseats would require a jeweler to set. However, they are not expensive and wonder if they are a viable option for purchase to bring with my stones when I drop them off to be set (not like I do that That often, anyway).
No, they are not at all like Snap-Tites. They are pre-notched settings that were developed and sold by Hoover and Strong. Here's a little blog on their use: H&S True-Seat The best thing about them is that the prong lengths are the same and the notched areas make great locating features. The downside is that they only work well for sapphires and diamonds. The pressures that the can place on precision cut colored stones would be enough to chip the upper girdle facet junctions, since those junctions typically have sharp edges, (as opposed to "native" cut stones which typically have rounded girdles). I particularly dislike their ideas and methods of setting princess cut styles. They have obviously notched the prongs so that the tips are to be bent down onto the corner all at once. This is a very dangerous way to set a sharp cornered stone and if the stone is softer or more brittle than sapphire you've got a 50-50 chance of blowing out the corner.
I think that these are designed to allow an untrained person to quickly knock out a bunch of set stones without having to think about what they are doing. Great for synthetic sapphire, not so great for a nice garnet. On the other hand, using these setting would take most of the guess work out of knowing where to actually cut the seat to fit. If you're going to use these at least make sure to remove that little bump that they put on the inside of the prong tip. It's designed to hold a stone in place while the prong is being bent onto it, but in softer stones becomes a perfect anvil for knocking the edge off the stone.
Michael pretty much nailed it. They are quality settings, and I often use them to reduce labor. However, I usually find I still need to tweak the seat a bit in some way, and usually do a fair amount of finishing and shaping on the prongs. I successfully set a pear shaped sphene (soft stone) in a yellow gold Tru-seat pendant today. Less labor for sure, but it still took a while to adjust the angle of a couple prongs, alter the seat a bit, and polish the metal. Not a DIY project, but if you are looking at them because you want a stone set in one by a jeweler, it''s a perfectly good option as long as the jeweler thinks it will work for the stone.