I'm italian & I bought a FOX Karambit (model 479, black finish on the blade & G10 grips), at first it seems good, I was pretty happy with it (I was low on the money, so I wasn' t able to buy an american model at the time), but the lock up really seems "underbuild" (sadly I bought the model on-line so I wasn't able to see the model before buying); so I put the FOX Karambit under the "Hand-pression test" (the test where you aply a moderate pression with your hand to the back of the blade), the liner-lock completely fail the test, it moves & almost disengage (only by a moderate pression by hand

& the knife had passed the break-in period).
So after this failure I come up with the "table test" and it failed again with moderate spine wacks, the liner completely dissengaged, I was so surprised & shocked that I have the bad idea to repeat the test the next day (hope is the last to die) & this time the blade deeply cut my right tumb (I was wearing a pair of kevlar "anti-cut" gloves by Vega Holster, they failed too) , when the liner failed again (I was gripping the Karambit with an extended grip, that seems safe to use but in the last wack I lost the grip on the ring & my tumb slip down to the failing blade).
You can see the pictures of the results of this test, here:
http://www.coltelleriacollini.it/community4/modules.php?name=Forums&file=viewtopic&t=5647&postdays=0&postorder=asc&start=0
In my review I also notice that the simil-wave used by FOX is less good than the original & the simil-Spyderhole is also inferior to the original (that is superb).
Another folder Karambit by FOX (the version with satin blade & alluminium handle) of another member of the italian comunity, failed the "table test", you can read about this here:
http://www.coltelleriacollini.it/community4/modules.php?name=Forums&file=viewtopic&t=5761&postdays=0&postorder=asc&start=0
(at the end of the page, author: Nomakk)
You can see better pictures of this "fantastic" Karambit by FOX here (new pictures with a new camera):
http://www.coltelleriacollini.it/community4/modules.php?name=Forums&file=viewtopic&t=7170&start=0
You can see the FOX vs Spyderco karambit (that I bought after the incident with the FOX & in my opinion is far superior).
Before this incident with the Karambit by FOX, I had others bad surprises with another of their product: the Sheridan, the "finish" (=extremely fragile paint) on the blade was coming of, by large piecies, you can read about this here (I had put a satin finish on the blade to fix this problem):
http://www.coltelleriacollini.it/community4/modules.php?name=Forums&file=viewtopic&t=5565
I really love knives, I have several models by several excelent manufacturers(Spyderco

, Benchmade, Bradley, Camillus, Emerson, Cold Steel...) & I have never had so many problems with a single maker, personally I will never buy again any model made by FOX.
Luckily I' ve not suffered permanent damage from the incident, but now I think twice before buying from manufactures that don't have a solid reputation (like for es. Spyderco, I have several models by them & they are perfect, they cost a lot here in Italy, but is money well spent).
I practise Kali (+JKD & Silat) & I love martial blades, in my opinion a SD folder must be safe & reliable, if not it is useless & dangerous (you can buy other folders but sadly you can' t buy fingers).
So I really suggest to you to take a close look to the Tarani 5.11 Karambit models, they have the front-lock (sort of evolution of the time-proven back-lock, that is my favorite locking system).
If you want a trainer & you have difficulties to find one, you can do it yourself, like me (from the "plastic" "cutting-platform" used in the kitchen):
http://www.coltelleriacollini.it/community4/modules.php?name=Forums&file=viewtopic&t=5530&postdays=0&postorder=asc&start=30
Use the trainer to learn the use of the karambit from a good istructor.
Take care be safe
P.S.:
Sorry for mistakes in the reply, like I said before I' m Italian, my inglish is not perfect.