Dunk, It is supposedly there to slightly smear inbound light across pixels to prevent the creation of artifact patterns. Removing it is said to give increased 'sharpness' but at the risk of artifact production. I recall that there are some photos posted on the web that demonstrate the difference and artifacts. Check this link for an example:
http://www.lifepixel.com/blog/anti-a...filter-removal
It has minimal spectrum affect like blue cast filter 2 does; i believe the spectrum passed is much like a Baader UV/IR Cutoff which cuts below Ha. There is a discussion on IIS about it in relation to filter removal pros and cons. It can be considered a form of dust protection as the piezo shaker function depends on its special dust release coating to function.
I removed my LP1 on my colour camera but later put it back because I was getting strange light leak like saturation of my sensor - putting it back appeared to have solved the problem - but I am usure if it was the actual cause. It maybe that I introduced the leak by removing the black plastic frame as well.
I am removing it on my new mono 450D, just the glass, as that will have no bayer colour matrix and I want all 12mega pixels as sharp as I can get them.
There is a discussion of its merits here:
https://www.flickr.com/groups/350343...918/?ytcheck=1