I am a big Karambit fan, but I have also been training with Steve Tarani since the late 90's. I dislike Pikal knives (not blade in, just the purpose built knives), so like a lot of things this stuff is personal. The key is the training. If you aren't willing to put the time in with any of these things, you are just another dude with a piano who can't play. While I don't like Pikal knives myself, I respect the guys who have actually trained with those who know how to run them like Craig Douglas. I look at guys with specialty edged weapons and no training with a bit of a humor. The key with a lot of people who make Karambits is what their training background is like? Do they know where the brakes go, do they understand the geometry and fit? If you want it because you want it, great....free country. I would recommend training, as Karambits in the hands of novices with no training are very likely to bite you. I spent six months with a custom trainer before I got the matching live blade, and have been very blessed to have not cut myself........the center consul of my truck was not so lucky, and I now use the trainer in the car as well.
I just hosted Steve Tarani in Houston last weekend and we spent a few hours on the Karambit. It is an eye opener for most folks, and this class was no different from the many classes I have hosted Steve for. People "get it" when they see it used correctly. I would imagine it is the same for those who get Pikal training from Craig or other dedicated practitioners.
As for speed.......I am pretty fast with a folding Karambit on the deployment side, and that is with a standard one. THe Emerson waved models are even faster, so that is a non-issue for me.