Since I own a fair number of cymbals from both Istanbul brothers, I think I can say with some certainty that Mehmet is a very good cymbal smith indeed, but Agop is even better! Don't be afraid of trying Mehmet's stuff when his models are different (there are some pearls there!), but when both have the same model, pay that little extra and get Agop's version instead.
This is true for the Paper Thin models. Both brothers make them, and Agop's are better. They have an absolutely gorgeous sound.
But Thomann only sells Agop's 16"/17"/18" models, so if you want a bigger or smaller one, you'll have to go with Mehmet.
Hence I tried this one. And it's definitely not a bad cymbal. I would rank it as top quality, but it's not "OMG the angels are crying" good. My 18" Agop paper Thin reaches that level, and it's one of the cymbals I often choose as a main crash (the 17" is another favorite). That 18-incher is a *sublime* cymbal!
My Mehmet 19" happens to blend amazingly well with it, and it is now my secondary crash of choice when I use the 18" Agop as main crash. It is much deeper pitched and really feels a lot bigger. A perfect partner!
But the 18" Agop is more flexible, since you can play ride patterns and bell on it as well as crashing it, and it works as a sweet and very bright mini-ride when played like that. The Mehmet 19" is more limited, and sounds best used as a crash alone. It may be big, but it's not a ride!
It also works best when played softly. It develops a ton of wash even at very soft hits, and gets very "noisy" when you hit it harder (I mean the cymbal gets overdriven easily). The sound sticks around for a bit too. I think the decay could be a bit faster, so I dampen it *slightly* with a couple of *tiny* pieces of gaffer tape. Don't overdo this!
While this cymbal doesn't reach the absolute pinnacle in sound and flexibility, it's still a very good cymbals that outclasses most cymbals on the market. For instance, it has a total lack of dissonant undertones (at least on my specimen, YMMV as all cymbals are unique).
All I'm saying is, don't let my hyper-critical nitpicking scare you away from it! If you want a very thin 19" crash, this one is a top choice.
I think it works best as a big second crash, paired with a 17" or 18" main crash that is thin or paper thin.