I know Alex's early stuff had some ridges. I have his Nike Zeus, both Little Joe's, and a V-2.
However, the Saturn 1B and the special release Pershing are quite smooth. Perhaps it's the new machines he's using. All I know is those last two were printed beautifully. Quite smooth.
I've not tried anything from Shapeways for comparison. John Pursely makes nice pieces as well.
I'm practically a disciple of John's and Alex's now.

Allen