I've got one of the Yildiz o/u in .410 bore.
I got it because it was/is built on a .410 sized reciever, not some larger "blocky" reciever. Also, I liked the way it handled, and pointed. It is stocked for an adult, the similar Mossberg didn't allow me to get a good cheek weld as it has a too high comb. Lastly, it has all the "expensive" features such as single-selective trigger, ejectors (not just extractors) and choke tubes.
Obviously it isn't fit or finished like a $1,500-$3,000 shotgun, nor is is it built like a Krieghoff. I didn't want that, an 9lb+ .410 shotgun........
For a "knock-around", utitlity gun that also really shines on the skeet range, I more than got what I was looking for. A friend who has several Browning .410 O/U's bought himself one too for a "loaner" gun when quail hunting pen-raised birds to keep his Brownings from getting "beat-up" by first time hunters.....
I easily knocked down all the doves that came within range on the opening day of dove season using S&B 3" #7-1/2's. Broke 20/25 on the skeet range the first time with it using Winchester AA-HS with 1/2oz #9's. First time I'd shot skeet in 4yrs........ Needless to say it shoots as good as it looks. And, on the pattern board, it shoots where it "looks", which also surprised me...
I really like mine and for $500, you won't find another o/u even close to it. I looked at the Mossberg which is very similar, but went with the Yildiz. I too picked mine from three that the store had on hand. It had the best stock wood, but also had some minor "dings" to the metal that were under the finish and occured during assembly/fitting prior to being finished. No, it's not a Beretta or a Browning, but again it didn't cost $$$$ either.
I don't think that you will shoot enough slugs or heavy loads through one of these to cause major problems. A steady diet of 3" mag turkey loads will show more effect on you than the gun....... Besides, most 1oz. slugs will "fall" through the bore on a cylinder or I/C choke. Be sure to avoid using the ImpMod or Full choke tubes with slugs and you'll be ok. Do try both barrels and cyl a and i/c chokes to see which shoots slugs closest to point of aim, which is more critical than absolute group size.