I've tried every major aiming system except 90/90, and I did try a simple version of that as well. I had some initial success on some shots with the systems and failed other shots. But after all this experimentation I have not found a system that works better than back of the ball/ghost ball aiming. Admittedly I didn't properly understand how to use CTE/Pro One until a couple of weeks ago (having only purchased the first DVD and apparently not being to smart, I misunderstood how to do it). After this I did try it a bit and the results were pretty much the same as with any other system. I would say that none of the systems worked perfectly for me. The See system did help a bit with some issues I had and was about equal for me to ghost ball aiming in terms of ball pocketing and I still use parts of it for alignment etc, but every system has had some kind of weakness or problem area that I can't work through.
My problem is not with aiming. That's what all this has thought me. I suspect that is the case for many others as well. Unless you can shoot a pool ball in diagonally the length of the table and follow the ball in with the cue ball perfectly with some degree of consistency, you should IMHO not even bother with aiming systems. At the times when I can do this almost every time, my aiming is not a problem at all, I suspect it never is. I recently broke the 100 mark in straight pool, which shows that I at least know a little bit about playing the game, although I may be a hack compared to many on the forum. The main problem for me is with delivery and alignment (mechanics).
For the last six months I have been working on line up drills on the snooker table for a lot of my practice time and it has showed in my game. My alignment and delivery is at a much higher level than before. I wish I had been doing this instead of spending all this time and money on aiming systems which have pretty much been wasted. Aiming systems might all be hoaxes as far as I know. None have worked better than ghost ball for me and other methods of training have proved to be far more effective in elevating my game. Sure, if your stroke is laser straight, but you keep missing balls on strokes which were otherwise well excecuted, then maybe you should work on you aiming. If I am honest I feel that this is the case with maybe 1 or 2 percent of my misses. All the rest are due to sloppiness in the PSR (especially rushing shots) or stroke errors. Be really honest with yourself when you miss a ball: Did you finish with the wrist perfectly aligned? Did you accelerate through the stroke? Was your body perfectly on the shot line? Did you chickenwing ever so slightly? Was your followthrough perfectly straight. Did you in fact hit the cueball at the precise point you attempted? All of these and many other questions like them should be answered well before you even consider spending any time with the act of aiming the ball.