For the KF5, I've seen the reviews go both ways, and some that didn't like it in the original state, like it comes, out of the box, but like it with the MTL kit (purchased separately) which tightens the draw.
I tried a 5 clone first because the reviews were so mixed.
I'm admittedly a total clone noob, I got mine on eBay.
I don't know who the clone is made by, the brand wasn't named in the listing, the boxes it came with are no help as they give no indication who made it, they all say "Authentic SvoeMesto.
I do want to point out that I've seen others who found "good clones", mine vapes well, but honestly, it's jankey.
The AFC, and the JFC don't feel sturdy, and it wobbles a little on a mod.
The wobble is mostly a deal breaker for me because it's very annoying, however *I* lean towards nit picking stuff like that.
I'd given it a Dawn soak/and good rinse, but it tasted like metal, so I'm guessing maybe machine oil, again...a noob here.
After 3 separate, LONG Dawn hot water soaks, that metal taste is gone.
Appearance wise, it's pretty much spot on as an authentic. I only noticed minute variations.
Because I liked the way the clone vapes, I ordered an authentic from Heather's Heavenly Vapes.
Hot water rinse, no Dawn, no wobble, nothing jankey. Lube your o-rings first. (Reference the SvoeMesto site.

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Obviously pricing differences will apply between the authentic vs. a clone.
I also have an authentic KFM3, to me, it's a little tighter draw than the KFL+'s, but not so much so that it's a deal breaker. It does not (or mine didn't) come with the metal tank, only glass. (The 5 comes with both glass and a metal tank, worth noting going into vaping doomsday, if it eventually comes to that.)
I do not care for the tiny deck on the 3. Again, not a deal breaker, just not my favorite to build on, and it's not a knock on SvoeMesto, if you want a smaller tank, the deck is going to be smaller. That's just how it goes.
It fits nicely on a ProVari Mini 2.5, the KF5 looks really nice on the ProVari Classic V2 with the P3 top.
These are just *my* personal experiences, and that's really all I can relate, what I've *personally* experienced and noted.
I'm also brand to Kayfuns in general.
I bought my first one KFL+'s this past May.
So, this is a new world to me too.
I'm not trying, nor do I want to, nor will I participate in a clone vs. authentic exchange.
I don't judge, and I don't care what anyone else purchases, truly...it's your wallet/pocket book, your call, and frankly, none of my business one way or another.
Whatever keeps someone off the stinkies is fine with me.
But, I will say...I'm leaning to liking the KFL+'s the best.
I don't know, I've only had my authentic 5 since Tues., so I'm still learning the ins and outs of it. So that opinion may be subject to change.
Sorry for the long post, but I wanted to put it all out there since you seem interested in these tanks.