I sparred a kali guy one time. Hard to hit and moved really well. I eventually got the upper hand but the sparring session stopped when he did some drop to the knee movement and uppercut me. Split my chin right open!
All in all, I've been pretty successful with my wing chun though. I do agree with others on here that it is more a developmental system. The biggest thing i think being body unification and overall upright balance. I know people have berated my kung fu brother for talking about rotation. But i do have to agree with much of what he said. I do think its dumb and dangerous to just go head first into someone over and over again. And if your going to stay there in range and not retreat why wouldnt there be rotation! I think the footwork is top notch to support that too.
Anyway, to be honest, the hardest person i've sparred has been my brother. He's very unconventional. More like a jackie chan, if you will. The king of shin kicks and wrist grabs and if an object is laying around, game over!
I had a good experience today. It was my first day back (class) grappling after having stopped many years ago. I managed to pull off a choke submission on one guy, an arm lock on another and very nearly a triangle choke on a third. Needless to say I got submitted too. It was very much a day of rediscovering certain muscles and having to take a long hot bath afterwards. I wish I was in my 20s again.