There are several reasons for the reliability and consistency differences in using topspin and draw. As for reliability, look at fig. 4.7 in APAPP. You will see there that the total range of cue ball deflection angles is about 5 times larger for draw than for topspin. With natural roll topspin, for example, the cue ball will vary from 0 degrees (straight on) on a very thin cut, up to about 30 degrees for a half-ball hit, and then back to 0 degrees for thick hits. But with draw, the cue ball goes from 0 degrees on thin hits all the way back to 180 degrees on thick hits. So, while draw gives you more options (which is why it is necessary on some shots), it also results in the cue ball path being more sensitive to the cut angle.
As for consistency, there is also the effect of ball-cloth friction. With topspin, the ball-cloth friction is working in your favor. As the ball is sliding on the cloth, the ball is always approaching the natural roll topspin condition. If the distance is large enough, then the cue ball always hits the object ball with the same spin/speed state (namely natural roll topspin) regardless of the tip-ball contact point. But this never happens for draw. Draw is a transient unstable condition of the cue ball, not the stable condition. With draw, you are always fighting against the ball-cloth friction (on the first part of the shot, before the cue ball hits the object ball). Different tables have different ball-cloth friction, so draw depends more on the table conditions than does topspin. And on bar tables, there is the issue of the heavy cue ball, of course.
>Also, I find
>myself FAVORING the 15 degree cut angle (to straight) over the 30 to 45
>degree position (which most players favor) for getting position on their
>next shot. Anyone else have preferences?
Yes, when you play position for draw, you almost always want straighter shots. And if you don't get them, you can't get the draw to work exactly the way you wanted. But if you miss a topspin position shot, you often can still use topspin to do the same thing (after accounting for any speed differences and such). You can see evidence in this sensitivity in the way your statement reads -- you favor a 15 degree cut angle (presumably with very little variation possible) compared to the 30 to 45 degree angle you would use with topspin position (with topspin, it often doesn't matter exactly what is the angle).
When I leaned to play pool some 30 years ago, I heard the expression, "Use draw for show; use follow for the dough". That's a good rule of thumb. At least it is a good summary of all of these reliability and consistency differences.
$.02 -Ron Shepard