i had horrible lock issues with numerous sifus myself, the smaller rekats didnt seem to have that problem like the larger sifu, the rolling lock, imho is very poorly designed and weak, especially with a long blade like the sifu, and its not hard to see why if ya have ever seen one apart or seen a schematic, IIRC a small OD pin locks intop a slot on the blade, tolerances are critical, no rekat should ever be inertia'd FWIW, even the smaller ones, its just asking for trouble, anyone reccomending a sifu for SD use is way behind the times, or the article is outta date, i loved the design (look at my user name) but after lock failures, with more than one, even after "babying" the thing, and having to deal with the difficult to deal with unfriendly staff at rekat, i moved on to something better( like a cammilus maxx bowie which would actually reliably lock up, go figure) and so did a lot of other folks which is imho why they went outta biz, the sifu got a rep for lock probs and none of the others in there line was ever very popular, and before ya knew it they were gone, and good riddance i say lol.
look at the archives, rather than suck it up and fix faulty locks and maybe improve the design to take the inertia from the long 5.5" bladed sifu, apologize to folks having issues, etc what do they do? go on the offensive and blame who else the folks who liked them the most, it was there fault the lock failed, they abused it, blah blah blah, its all still there i'm sure.
but, like i say, the smaller ones didnt seem to have the problems the sifus did, BUT they never sold near as many of the smaller ones either, like i said imho its a crummy design very intolorant to any abuse/debris/sometimes even normal wear, so dont ever even think about inertia opening the things, if they break i know of no one who will fix the things anymore, they have been outta biz for i bet 10 yrs now, also beware of pocket detritus/etc, its easy for funk to get in there and cause lock up issues.
i get mad every time i think about them lol.