I've had the STC duo and now the optolong l-extreme. Both great filter.s I did 6min subs with the duo but am doing 10min with the extreme as it is narrower especially around OIII.
I would put up the Helix I've just finished capturing. But looking at it this morning there's a terrible light artefact that I've just realised is coming from a hole the the back cover on my newt. So instead here's the Eagle Neb I did a month ago
http://www.astrobin.com/uzwzm1
I got mine from Cyclops Optics