I have a Vikuiti DQC-160 screen protector laying around right beside my monitor. Of course I can't say anything about it - since the N900 itself isn't even shipped yet. My decission for Vikuiti was based on quite some reasearch in several PDA and smartphone forums. Durasec only got very mixed comments, especially a sticky film when removing the protector appeared in some comments. Vikuiti protectors recieved basicly complete positive comments. In addition to that, schutzfolien24.de offers free shipping for germany. So I only paid about 9,- €uros for the protector. Delivery was fast, ordered on sunday evening, it got shipped monday morning and I got it on tuesday. Their international site would be protectionfilms24.com, just search for the N900.
Got the Vikuiti DQC-160 screen protector for N900. It looks very solid and is of the type you can remove and replace anytime without problems or residue. One slight problem, it is a bit too large - I used a straight-line paper cutter to cut a millimeter or so from two sides and now it works great. Absolutely lets the screen shine and so far no problems with touch working with either finger or stylus. I'm getting some more for future replacement needs. But beware, a bit cutting may be required if all are a tad big for production units.