The problem I saw with the silverstone was that it has a speckle effect to it that doesn't match up quite right. Are you in the sac area (auburn)? If so, you might want to try aero colours which does an amazing small area paint match touchup. If I had known about these guys to begin with, I would never had done all those paintchips by hand. The sac local forum just had a recent posting about them.

 

metallic particles are just plain hard to deal with... specially if you're using a paint pen. if its spraying, then theres no problem, coz they kinda correct themselves as you spray... but i wouldnt recommend a DIY with a rattlecan spray.
on a side note, i touched up my mom's rav4 S it was graphite gray micah or something, the metallic particles tend to stick together when i used the touch up paint...
BTW thez99 do you have a pic of when you did the fix on the key mark?