I guess, the 520 series is a knife you love or not. If you have one, those aluminium scales may make it hard to trade, for the scratches they may have or ppl. fear to get. But all in all i think, they are not that spread inside the knife community.
As the 5000 came out back in 2003, i fell in love at first sight, with that knife. I got the 5000A as they came out here in germany and the 520 some time later. I have used the 520/5000 models over some years. I have get a custom blade for the 520, just because i wished for a tough carbon blade. I gave the 520 a rest and walked around for long with a small fixed blade and with the 14205 too. Now i have come back on the customized 520 and i still enjoy that knife, even though i see all the pros and cons considering other knives.
Considering that strong handle, many ppl think about a thicker blade. Me too.
Maybe that is the point where the Model 14205 comes into play (G10 scales and a thicker blade).
But i can stand the scratches. It isn´t nice but it isn´t important too.
I see (even though i don´t feel), that the blade doesn´t have to be thicker. For what? Try to break it. If it is not the blade, it is the handle that may crack first. Consider an Strider, it will be the handle. Where is the difference?
Consider the weak point of the blade: The tip, i have just have held one SnG in hands and didn´t found much of a difference between those blade comparing just the tips. Where is the difference?
A bit more steel just for the better feeling may be ok, but in fact is not needed. That blade cuts very good and is strong for every hard knife job. What can´t be done?
I don´t talk about prying, since i have read a report about someone, selling Strider knives, "prying" open a Roomdoor by in fact breaking away piece by piece of the doors wood. That job can be done with a lot of folders, with the 520 anyway.
The overall weight of the knife and the overall strong constuction makes it a versatile tool for every edc jobs. Cutting branches with a single blow, cutting cardboard with ease. What can´t be done? I don´t know. I have read about someone, who pryed open a window with its 520. He trusted that 3mm piece of steel more, than maybe others their 4mm+ pieces.
It can´t be a weak knife.
Benchmade has advertised the 5000 as the best tactical folder in the world and invites to ask why. They wrote in their black class catalouge, that they have done some tests with that kind of knife. I am very curious, to know, what they have done. Maybe someone takes the time and finds out. Not me.
Self defense? I am not into self defense too. But the long handle may make it a good defensive tool just as a kubotan.
Back to the original question:
The times you find it/ or not find it in the sales does not reflect how good that knife is.
That doesn´t have to count for any knife. It´s just my opinion on that particular knife.