I got Vikuiti DQC-160 and invisible shield and i got a say i like the IS more. I just couldn't get the Vikuiti perfect. There where always left some bubbles. IS needed one try and it was pretty much perfect. After 2 days there is no single bubble or anything and i don't find the surface to be any trouble.
Ordered the Vikuiti because my IS order did take 17 days to ship and after hearing bad comments about it, but i'm really happy with IS and it will be the one staying on my N900.

Thought one really good thing with Vikuiti is that it was easy to take off and shouldn't be problem to put it back and i do like the coating.