I'd say a Fuller or Krebs is higher quality in the same way an Arsenal is higher quality than a typical basic pistol grip conversion saiga.
This can be true. It depends on a number of factors, including where the prices of saigas are at when you buy. Saigas prices over the last at least 5 years have risen and fallen many times. Right now they are as high as I've seen them, making various other AK options more attractive, in terms of price/value. One other thing to consider is economies of scale. Will you only get one rifle, or will you add a x39, and a 5.56, and a S12, and a 308, etc?
While I have not seen the whole universe of home conversions or even a sample from which I could reliably extrapolate, I would imagine that is probably correct. However, I think that begs the question of why they don't. I believe it is because functionally there has proven no deficiency in doing it that way. Back when I used to be more into Saigas, and was acquiring multiples of various calibers and configuring them to best serve my uses, I devoured basically all the info I could find online about them and modification folks were doing. I've never seen someone report any function issue caused by any of the things you list.
I think that is a fair question. The only one of the three I see actually having any kind of durability or reliability issue whatsoever is the screwed on trigger guard. I would imagine that a properly riveted trigger guard is in theory more durable or reliable than one screwed on and fastened with locktite. However, I also believe this is a theoretical advantage. I have never seen or even heard of someone's trigger guard coming off when attached by two (or even the one screw method). Users may not take such guns to war, but I know of a number of folks that take them to hard use carbine classes and use them about as hard as civilians can or will (without intentionally trying to break the gun). I think the type of forces that would damage the screwed on guard would also damage a riveted on guard. The more valid concern would be the screws coming lose. I do not think it is very likely that two loctited screws are going to come lose at the same time. Even if they did when one uses that method there is enough tension on the trigger guard that it alone keeps it fairly secure. If however it failed, so what? It would be inconvenient and bothersome, and one would need to reattach it. However, it is not a critical part to the gun functioning. It is not like we are talking about a bolt, or a carrier, or other vital part.
I tend to prefer the methods that make the gun best serve my purposes. A simple example is that I prefer to use a retainer plate to the OME method of retaining the FCG. It is better and makes the gun much easier to service.
I agree fully with that. I personally don't find it compelling to say that a riveted trigger guard is worth a the added cost (which again one could do it, including acquiring tools for less). If it is to someone else, I certainly cannot tell them they are wrong.
I tend to prefer the best for my purposes I can get as well. This is actually why I personally wouldn't ever own an Arsenal (that and their financial support of Harry Reid, but I digress). For the money I can get a configuration that works much better for how I use my guns. To me there is no sense in buying an arsenal and then tearing it apart and building it into a configuration much better suited for my uses.
I do think arsenal's tend to be most attractive when one wants the particular configuration they come in.
Not credentials. It is asking the basis of your opinion. It is one thing to have an opinion, it is another thing entirely to actually have it be based on something. When someone wants to opine, I think it is perfectly reasonable to inquire into what experience they have informing that opinion. I've noticed that people that actually have a significant amount of experience with things tend to have opinions that differ from those that don't and from what everybody just knows. If you'd like the answers to those questions I'll PM them to you as not to derail this thread. Just let me know.