First of all, what exactly do you mean by a bead? Rocs have beads, Aviars have beads, but a Predator? I take it you are referring to the increasingly sharper concavity towards the bottom of the wing. Anyway, this is not the only difference b/w the Pred and Avenger. Look at the wing and notice that before the bottom of the Pred wing gets concave, the outside part of the wing is almost convex. This somehow gives the Pred stability and speed because the first runs (original Pred mold) were different (straight rather than convex front wing). I think that the Predator is faster and has more carry than the Avenger because of the convex front part of the wing. The Predator also gets what I would refer to as lift or an air-bounce right out of the hand, that an Avenger does not. Switching a year or so ago from the Firebird to the Pred I really had to adjust to that lift. On a sad note, I lost my 1.4 years seasoned Pred last night...
About the Flash and Surge: The Flash is a truer flyer, but the Surge is more HSS. They are both versatile depending on your armspeed.
Great post! I found the same lift on the Pred, especially if thrown hyser into the wind. The point is if I can use one mold in place of two I will. I actually have plenty of Avengers, I just noticed that the Avengers I like have flights nearly identical to some of the Preds I have, and Pred will never let you down, where the Avenger will sometimes catch a gust of wind and lose the line. I do have some pig Avengers that are basically indistinguishable from my Preds for the most part.
As far as the Flash. I have a max weight yellow Z that is very overstable and can be flattened from a hyser into a headwind and not flip and will fade skip like mad. It is kind of like like a Crush. I use the ESP Flash for most of my "normal" straight work that used to be the flippier Avengers, but the Flash is so much longer you can throw it so smooth and it just goes. Mine are domey and are all tuned to the same stability, they do not flip unless I want them to flip. Many of the ESP are flip out of the box, but a little tuning solves that. If I had to live with the stabilities of the fast drivers as delivered, I would go crazy. Luckily, ESP tunes so well, and tunes permanently.
I think the Flash is faster and more predictable than the Surge when tuned to the proper stability. I have definitely thrown the Flash further than the Surge.