BGfisher

A peep without a tube has several advantages. There's no tube to break or be slapping the cable(s) making a bunch of noise and fraying the cables. They are lighter which equates to more speed. Usually you have a wider choice of peep sizes if you're one to bracket your sight guard.

The problems you are concerned about, the peep rotating when drawing, are usually a product of poorly manufactured strings, which is what you get from the factory in most cases.

When strings are made well, they are prestretched and pretwisted, then served. This makes the strands tighter within the bundle and evens out the worklaod each strand is doing, ultimately reducing or eliminating string twisting (peep rotation) as the bow is drawn. Sometimes another side affect is a gain in speed, as much as 10 fps, depending on which materials are used for the string.

Probably one the best reasons to get good strings is that once they have about 50 shots or so through them you can set up your bow and tune it and be relatively certain that peep rotation will be a non-issue. Also the bow will hold it's tune for a much longer time, usually till the strings need replaced.

This is why, as more people get educated to the fact, more are starting to rig their bows with good aftermarket strings. Another biproduct is that a few (not many) manufacturers are starting to make better strings or rig some of their bows with strings from a few custom string makers.