The article in question is from Artie Morris, who I personally hold in high regard (even if he does live in Florida
).
Note that the lens pen in question is not the fat one we see in the shops over here, it's the thinner
model.
Re the issue of residual carbon: a lens pen should be used in conjunction with a blower.
Personally I get by with a blower most of the time, and have an Arctic Butterfly brush and a full wet-clean kit for when something needs to actually touch the glass. I haven't been tempted by the lenspen path for DSLRs, although I have been known to use one on the IR filter for DSLRs when servicing a camera... (i.e. with the filter out of the camera and in a gloved hand).
Craig, you say your lens pen struggles: is it due for replacement? They don't last forever (the head wears out, and the reserve of powder gets depleted).