The WK180 has a carbine length barrel where as the the Siberian has a mid length barrel which makes a difference to how the rifle shoots. I think that you should be able to take the gas system apart without having to remove the gas block which is currently necessary with the Siberian. It has been mentioned that both of these recent reviews where done using the same rifle, so the same problems showed up in both reviews, it would have been much better to not have used the same rifle for both reviews! However I do think the reviewer is very competent.
I'd like to know which warranty work was done at BCL. They are pretty forthcoming replacing even a whole rifle if needed.