Thanks all.
Its always an interesting question whats best, few long exposures or lots of shorter ones. Perhaps one night I should try a single hour long one (if I can concentrate that long lol) at ISO 200 with the filter on and see what happens. Without the UHCS filter, I cannot go much past 10 mins @iso 200 without getting too much sky fog. Id love to be under a real dark sky and be able to do 10 or 20 mins @iso 400 without filtering and not get skyfog.
This is the scope setup I use
http://www.users.on.net/~josiah/focuser/IMG_9932.jpg
The mountand scope was made by Astro Optical Supplies in Sydney, and has not long had its 20th birthday, getting it just in time for helleys Comet. The large off axis guider is newer, got it last year.
http://www.aeroquest-machining.com/page9.html
Scott