I don't think roughing up the surface of the stem is going beyond what I would expect, but that's me (even though I haven't even had to do that).

I have had to do it on various other bikes and parts that ended up having slightly slicker finish that what the designer specified.

Unless there is something wrong with the part, I do not see any other needed solution.

Here is an example of the the anti-slip compound I was refering to if you really feel it is required (It's called liquid torque and there are various other brands).

http://ritcheylogic.com/web/Ritchey~...3858&live=true