Here's some issues I have with the leveling system from RS. The tool that clips on the string has two axis levels as you can see in the pic. The top level is for leveling the bow straight up and down from the shooter's position. On some bows (like single cams) the string does not go down the middle of the limbs. The top idler wheel may be centered in the forks, and the entire bottom CAM may be centered, but the string track of the bottom cam is to one side of that cam. The cable track is on the other side. So you may be getting the STRING straight up and down, but the riser/limbs may be off a tad. And if you are trying to level a sight or scope for 3rd axis, you need to know this.
And if you clip the device on the string (like the picture with the arrow), the top clip may be on your center serving area, but the bottom clip may be on the bare string. Depending on how thick your center serving is, it can make a difference in where your level reading reads "level".
Very well put BF. I came to many of the same conclusions. It has its drawbacks with certain applications, like the string angle you mentioned on a single cam, but I found them to work pretty well in getting you closer than the just a bow square, etc... Used in conjunction with a bow square I have found the results to be pretty accurate. As for the secondary level.....I have not really used it to adjust the sight level but rather prefer my older method for that.
Iak,
They are available at a variety of archery supply places. I found several by just using a search engine on the web. Probably the most well known is Cabelas. I have seen the bow vices advertised anywhere from $40 to $80 depending on make/model. The level kit is usually between $10 and $20 and the laser center shot tool goes anywhere from $65 to $85 most places. The one in the picture is the "hunter" model. There is also a "pro" model that has microadjustment features.