Same as title. I've put it on, but I don't know if i notice a difference. I guess if i don't notice, it's not really doing anything then huh? lol.
Skill recovery only affects the 3 skills, blue, yellow, and red. So if it's a skill grapple like the ones on the Gunner, Sniper or Assault then yes. Left trigger grapples are not skills so skill recovery does not affect them.
Not to be an *** by arguing with Scathis, but I think it does speed up Grapple's recovery. An Assassin's grapple with the gold Speed Recovery endorsement recovers in about 10 seconds. With no recovery, it's closer to 15 seconds. I tested it while grappling bots in an exhibition blitz match, and also with a friend during a 2P private Crossfire match. Try it yourself- there's a circle in the middle of your screen that tells you when your grapple is ready again. As a sidenote, the above only reflects recovery after a successful grapple. I didn't time recovery from unsuccessful grapples.
As the Red name said, it does speed up grapple cooldown. I original thought it didn't until I tested it. I just assumed it wouldn't as grapples tend to be 1-hit KOs. Currently I'm filling in the values for grapples for Sniper, Gunner, etc but you will be able to find the information here
Apparently skill recharge does. :/ I don't know whether to believe Scathis, or the people who actually tested it, and says it works.
You don't have to do anything scientific to see for yourself. Have two assassins (one with gold skill recovery and one without any skill recovery). Start a blitz match, successfully grapple something, and spam until you can grapple again. Switch to your other assassin and see if you can tell whether one recovered faster. There's about a 5 second difference, so it should be recognizable without a timer. You can also pay attention to how quickly the circle in the center of your screen refills after a successful grapple.
Wow, if this is true, it will totally change the way I'm using my sin. Or perhaps I'll just have one shuriken set up, and one grapple set up.