Andy,
I have a set and can assure you that the quality and fit are superb. I'm really happy with the pannier per se.
The attachment mechanism is very secure, wth boxes are watertight and the locks are good (I only ever lock one if there are valuables in there) and the welds are good.
On the downside, I ended up fitting a simple aluminium plate heat shield to protect the left hand indicator from melting, which it did twice. Seems to have solved the problem. The reason for it arising is the angle of the exhaust after fitting a Remus Y piece, the hotter gasses and the revised position of the indicators. Jesse supplied an extension tube, but the plate makes this pointless.
It's all easy to put together and protected by a finishing coat, but I thought it worthy of a coat of black paint to protect it further.
I recommend them and am really pleased I didn't buy the BMW boxes. Main reason is the bike looks awful when the boxes are not in the carrying frame and the locking system is fundementally flawed in its design. I believe that Vern's boxes are very good.
I'm in Manchester so it's unlikely you will see my set.