I agree and disagree with the points being discussed. From experience I can tell you that chassis stiffening mods can be actually quite dramatic even at low speed slalom style turns. For example, swaybars are something you can immediately notice after installing them even if you aren't doing time attack laps in a suburban neighborhood. Hell, I tripod going up driveways and gas stations. On the other hand, things like strutbars you can't really notice much, if at all, on the street because that requires a bit more stress to make a difference. I wouldn't doubt it though, if someone who tracks their car told me they feel a difference when taking offramps with their new strut bars.
Now... I've heard plenty of of people with GT spec ladder braces (on different cars) say that they do feel the car is more planted, predictable and consistent after than before. I've never installed a set myself so I can't comment on those specifically, but I wouldn't put it past someone with a good feel of their car to notice a difference with a chassis stiffening mod.
This is a mod I would definitely do, but I can't because of clearance. I like it though.
Jeff, if you can ask them if they wanna send one over to florida for some flogging