There's a thread over on the CR list at the moment. Some fellow asking about recommendations for 27 X 1 1/4 rims. When I posted that I like the Sun M 13 II rims I have, two wheelbuilders there piped up and said they both thought the rim was junk. Problems with the joints, un-even tension, not flat, etc., etc.

I haven't noticed such problems with that rim. Though I have only built one of the two sets I have, and, I'm no pro wheel builder.
Anyone else have issues with the Sun rims?