I've had the U9BL-S for almost a week now and still loving it. As Corland said, the key caps could be a little more substantial, however I think it's good that they're nice and light, thicker keys might make them actuate a bit too easily. It's interesting that you mention Filco though, I thought one of the main complaints with Filco was the keycap quality, how they're thin and the legends can wear off quickly.
For my uses, this keyboard is just very fun to type on and great for gaming in a dark room. The soft matte finish feels perfect, it feels exactly like the wide grip on my Logitech G9x mouse, I even set the LED color on the mouse to blue so they match.
