Oh yes. Very rare in deed. I have seen one, the upright type with a 20'' monitor in a smaller arcade in London years ago. By chance I should add. As I was walking past the windows of this arcade with a friend of mine, actually she was in a kind of hurry but I think that I cried out something like ".. uh,.. Solvalou? ..", so we went inside for short visit. I played it a couple of rounds, ofcourse at the time being too excitied to manage the sutiation, I wouldn't even be able to tell you the color of my eyes. And ofcourse this was in the time before digital cameras so no pictures were taken. But certain impression stayed with me through the years, like; I remember that the analog joystick wasn't very comfortable, and the cabinet har lots of blue on the panel. I think the arcade was somewhere near Soho.
And, I even spoke to namco about Solvalou. As I returned from London where I was working at the time so I did some commuting back and forth during a period, having seen Starblade I immediately called namco to find out the price. "£2500" - oops. Big money back then for a young lad like me. But somehow the receptionist mentions Solvalou, and that it was similar to Starblade but not as successfull. From that moment I started the hunt for this illusive game, Solvalou, because "like Stablade" it had to be polygons made by namco, and that was enough for me.