> Another obvious point is a particular flight mode: glide ratios will be different for full flight, half-brakes, rear
risers or a combination of them and brakes etc
Not exactly, Yuri. Glide ratio is glide ratio. Full stop.
Glide ratio for an aircraft, for a canopy, for a paraglider, etc., is by definition "the best flight capability of that particular wing" which depends only by its geometry (which consequently affects its aerodynamc properties) and is a unique number.
"Glide ratio" of a "wing" is the maximum possible ratio between distance flown horizontally and distance flown vertically.
If you put yourself in the same conditions prescribed by the manufacturer you are going to achieve a flight path corresponding to the "glide ratio", that is, you can reach the maximum horizontal distance possible for that particular wing, that is again, the "flattest" trajectory possible with that wing.
Anything different from the "particular conditions" given by the manufacturer of the wing, will yield a flight path that is worse the "thoeretical one".
Example: the glide ratio of an aircraft is 12. But in the manual of that aircraft it is also written that you can achieve the "theoretical" horizontal distance given by the glide ratio (for the height at which you are) only if you "put" in the wind speed meter THE speed for maximum horizontal distance flown. And obviously you don't have to put flaps on your wing!!!!! That, ONE SINGLE speed for that particular aircraft. Having the engine at minumum, any speed different from the "maximum efficiency speed" (i.e., either slower or faster) and any other configuration of the wings (i.e., flaps on), will cause your aircraft to fly "worse" than the "best possible glide ratio flght path". You don't reach the "target" if don't fly AT that particular speed.
Coming back to out parachutes. Of course, each parachute has its own "glide ratio", that is the ratio between horizontal and vertical distance flown, in the best conditions, that is, full flight, canopy fully pressurized, best wing load for that canopy etc etc.
Now, from the flight corresponding to the "glide ratio" trajectory (=zero brakes), you can move on and apply brakes, make turns, and so on. Of course, doing so you "worsen" your "theoretical" glide ratio flight path (i.e., straight in approach on a tight landing area, you fly straight applying half or 3/4 brakes and so on, so "worsening" your flight path with respect to "glide ratio" flight, but doing so you land wherever you want!!!).
To summarize: "Glide ratio" is a geometrical/aerodynamical property for each wing such as you can reach the maximum horizontal distance possibile for that wing ONLY IF you fly that wing in the best possible conditions (stated by manufacturer). I.e.: if you are good, you can approach the "glide ratio" flight path (=you apply zero brakes), anything different from the "best conditions" will make you fly worse than the "glide ratio" flight path.
And, obviously, given for granted all the important features required for a BASE canopy (opening fast and on heading, with and without slider, etc), a BASE jumper would prefer to have a canopy whose glide ratio is the highest possible, so that, if you want/have to fly long distances, you can, if you want/have to fly short distances (=straight in approach), you simply "worsen" the "glide ratio" flight path applying the right amount of brakes.
My 0.02 €.
Stay safe out there
Blue Skies and Soft Walls
BASE #689
P.S.: My numbers (i.e., glide ratio of 2.20) were taken from a whole flight where I flew at full flight (zero brakes) and only applying brakes to make turns. So it is an average experimental glide ratio for a standard flight (where you apply brakes from time to time to do turns/correction of trajectory once in a while!!!).