Expensive items. But I suppose all metal panniers are pricey.
My two-penn'orth of experience...
a. The hinge on all 3 panniers is a serious weak link - it's all too easy to open the lid too far and break the hinge. Once possible solution (which so far, has worked for me) is to place a length of webbing betwixt the lid and the pannier so the lid can't go beyond 90 degrees (i.e. vertical when open) - existing screws on both lid and pannier can be used as attachment points.
I do prefer the pannier design on the 1200GSA where this is concerned.
b. Labels all over the panniers tell you 5kg is the limit. Which for panniers that size is a bit laughable. I do my weekly shop using the bike and don't care to think too much what weight actually goes in them.

I beleive the subframe gives way if anything is going to give - there are other threads showing how and where to weld strengthening braces - didn't Messrs. McGregor and Borman suffer a broken bike thru' overloading it with luggage on their initial safari?
c. The feet on the panniers are a bit weak in the attachment arena. Only matter when they are off the bike and standing on the ground really. One of mine has broken off but I can't get a replacement and my usual answer (JB Weld) failed to work.
d. Likewise the fixing brackets (the bits that lock the pannier to the frame) can be a bit fragile, when the bike goes over. DAMHI... I managed to repair mine with a pop rivetter. Quite proud of that.
e. They look far better than plastic panniers.
f. Despite all my criticism above, I am glad I got mine when I got the bike - they have earned their keep over the years. All in all, they have maintained their good looks with no real lproblems re corrosion or other osues.
g. Hell's bells, but they are pricey.
HTH
Bill