I’m not 100% sure on what this variable does and does not affect, however for the most part lowering the variable makes AI and player autopilot fly “tighter” routines - for example, if this number is set low and an object is in your path, autopilot will meticulously (and quite slowly) fly you around the object in a precise manner.
In contrast, if the number is set high and an object is in your path, the autopilot will lazily guide you around the object, possibly smashing you into it.
My best guess is that this value is some sort of “delay” for AI-related functions, seeing as low values make AI quite precise with their functions and flight patterns, while high values make them a bit more “lazy”. It could also be a distance multiplier of some sort, depending on the function, as using values that are too low will remove the ability for autopilot to cope with large objects such as planets, and NPCs will attempt to tractor items that are beyond their tractor beam ranges. Setting this number to a negative value yields extremely bizzare results with the AI that I am still experimenting with from time to time.
88 Flak’s FLHook versions - found at http://the-starport.net/index.php?option=com_smf&Itemid=26&topic=1749.0 - feature the ability to modify this value on-the-fly for FLServer, meaning that (server-side) AI NPCs and (client-side) player autopilot can use two different values - this allows client-side player autopilot to use normal values while allowing server-side AI to use radical values (such as negative numbers).
M0tah has done a little work in dissecting various functions to point to other variables instead of this single global “AI helper” value, so that individual AI functions may be tweaked more carefully along with other variables (see the “Unfinished” section of the Limit Breaking 101 topic).
Finally, the FollowOp nonsense is a bit of a personal note, in reference to my AI Wingmen functions that have AI NPCs use the “FollowOp” directive to follow players. This variable has enormous control over the function, with negative values yielding 100% accurate follow behavior (they even follow your strafing patterns).
Edit: So, in short, if you want a “lazy” AI that flies wide, stupid flight patterns (and crashes into stuff left and right), use large values like 2.0 or 2.5. If you want a meticulous AI that flies by-the-book patterns (and is generally rather slow at accomplishing tasks), use lower values like 1.0 or 1.25. Dipping below 1.0 has unpredictable effects, as does dipping above 2.0. 88 Flak uses an exact value of 1.34, as this yielded reliable routines while not screwing over AI distance checks. And they’re still fast enough to keep the hurt on.