For the sake of converting uptimes into percentages, when theory crafting I use 180 second (3 minute) encounter lengths.
All of the Blade Dancer cooldowns have the same possible uptime, as an individual ability, and receive the same uptime increases from talents. Something to note, however, is due to exhaustion it is impossible to have 100% uptime of cooldowns should they be used in sequence. The specific selection of cooldowns will vary the uptime of your total cooldown usage, due to the fact that Blade Tempo has a shorter exhaustion period.
The uptime conversions are as follows: (Rounded to the tenth)
15 second durations, twice in 180 seconds, for a total of 30 seconds or 16.7% uptime.
When 3/3 soul points are in BDR T6 Blade Hustle:
21 second durations, twice in 180 seconds, for a total of 42 seconds or 23.4% uptime.
Each point being worth 1.8% uptime.
Hope this helps-