There are some key differences. One of the biggest weaknesses of other fowling piece options is the large forestock. By this I mean it's height. Original (and therefore quality contemporary) work have forestocks with a thin web resulting in the height to be a minimum. The ramrod groove / hole of these often follow the barrel profile to allow this. We take great care and pride to recreate this. When I see other offerings with the huge forestocks, it screams at me. To anyone who studies this sort of original work carefully, I suspect it does the same for them. These large forestocks are chosen for ease of manufacturing. Drilling ramrod holes with thin forestocks can be pretty difficult. We've worked hard to solve these issues.
The next point is the barrel. We've worked hard to produce barrels with a minimum wall thickness to match original work. Our 16 gauge is around 1/16" at it's thinnest point. I'm pretty sure no other manufacturers work to this thickness level. Often barrel wall thickness are excessive and result in a poor handling and heavier than necessary piece.
Since you brought up Chambers locks... I used Chambers locks for years on custom guns, and they can work well. But, this is often only after some work. Why? because the manufacturing methods. I would generally spend the better part of a day working on a lock to make it operate at a level I was pleased with. Our manufacturing methods result in much more precise and consistent products. A few other details regarding locks... We took great pains to capture the details of original English convex locks of the period. In my opinion details from other manufacturers don't stand up as well. For example, the pan on one slopes down towards the buttplate. The pan bridle is also oversized and meets the pan in an odd fashion. The pan cavity is generally mishapen. The cock is overly thick as is the plate and pan cover. The internal bridle deviates from typical English design and is kind of a mess in my view. I can say with a straight face, our locks are a step above.
Finally a point to be made is the quality of workmanship as you would receive a kit. I'm not talking about how complete it is, but rather the quality of the work. For example, inlets from other manufactures are at times oversized or not in exactly the right spot. Point is there are commonly issues (some small or some pretty big) that might have to be dealt with. Our processes and manufacturing methods help minimize these sorts of things.
The last is just the general conformation of all the many details that make up a quality English fowling piece. For example, pretty much without exception, the guard bow is generally rounded and fairly small on English work. In some offerings you see this is elongated and misshapen. Things like this scream out to someone who is well versed in English work from this period. There are other examples as well.
I hope this explains things and helps provide a better understanding.
