Hi Luka,
Definitely can recommend a light pollution filter. My setup only allowed 70 second subs before the background light pollution destroyed subs, after buying an astronomik ccd cls, my sub length went up to 3 mins and dramatically improved my images and made processing way easier too. I can't recommend a LPF highly enough.
with regards to NB, I did quite a lot of experimenting with my modified DSLR and NB filters. my plan was to eventually have a ccd but I had to stagger the expense out and bought my NB filters before the CCD (couldn't think of something more frustrating than having the camera but not having filters!). I wouldn't recommend using the Ha as luminance as the reconstructed/debayered image is a quarter of the resolution of the colour image. As Glen has pointed out noise is the killer for dslrs and NB, long exposure and uncooled is a bad recipe. still you can get some alright details on the brighter objects.
I tried very hard on some of the dimmer ones and just couldn't get over the noise issue. I used 2" filters as I was going CCD later on, you are able to use 'clip in' filters on a dslr.
http://www.bintel.com.au/Astrophotog...oductview.aspx
Here are some examples: including NGC 6164 normal, Ha and Oiii blends - probably my best NB/RGB blend with a dslr. I think that is the way forward rather than using it as a NB only option.
Eta C Ha
https://www.flickr.com/photos/803366...posted-public/
No NB
https://www.flickr.com/photos/803366...posted-public/
Ha RGB
https://www.flickr.com/photos/803366...posted-public/
Ha Oiii RGB
https://www.flickr.com/photos/803366...posted-public/
Russ