Symmetrical balls do have a max bias (PSA). If you draw a straight line from the pin through the CG, the max bias will be located 6-3/4 inches beyond the CG on that line. Because it always falls in the same place on symmetrical balls, it doesn't need to be marked. After a symmetrical ball is drilled the MB will be located elsewhere.
PSA and dual angle are the same with different nomenclature and methods to determine positions on a ball. Any dual angle grip can be defined in PSA terms and vice versa. For example 'pin-buffer' in PSA nomenclature is the same as the VAL angle in dual angle. A shorter pin-buffer is the equivalence of a narrower VAL angle.
As for pin-up and pin-down, check this video;https://www.youtube.com/watch?v=dxx62iJGfGk
There is a difference, but allowing for the normal variations in a person’s delivery, I’m uncertain that difference is significant enough to consider in drilling a ball.
I think it would be interesting to have a ‘blind’ test to see how many people could actually tell how a ball was drilled if they couldn’t see the pin, CG and MB. I use to believe they made a difference, I no longer do. I’m now of the opinion drilling only accounts for 5% or less of a ball’s reaction and is reduced by a bowler’s speed and RPM’s to a point that it is indistinguishable from normal variations in delivery. For those with higher speeds and higher RPM’s the opposite would be true.
I own a pin-down Storm Lock and a pin-down Storm Hy-Road. The lock, based on the Perfect Scale' is 26% more aggressive, yet, both begin to transition at the same point for me, and the Hy-Road actually has more motion. A video shows the Hy-Road retained more speed and RPM's which created a stronger back-end. I was able to recreate the same results with an Ebonite Cyclone and a Storm Lock drilled 50 x 5 x 50.
I guess what I'm wondering is, are bowlers really understanding what they are seeing on the lane or simply repeating what they think their ball is doing based on what they've read or heard.
Until I started drilling my own equipment, I thought all the values had some meaningful impact on my delivered ball. I no longer believe that.
I'm now beginning to think we've been brainwashed by advertisements and hearsay evidence to the point that we see what we believe not what is actually taking place.
I've been bowling since 1961 and only in the last 2 years have I begun to question what I read about bowling balls. What started out as an effort to find the best drilling configuration for myself has simply led me to believe I can drill a ball anyway I like and the difference will be negligible. Additionally, high-end balls are only useful for 5% of all bowlers. The rest of us mere mortals can use a lot less ball and save a lot of money in the process.