Welcome to IIS Dave
The 6SE and 8SE are nice little scopes when you need something easily portable and invisible to SWMBO
The 6SE can literally be picked up and carried in one piece. The 8SE with the bigger tube is not so much heavier but a little bulkier to carry in one go. However, they separate neatly and tuck away somewhere easily for storage.
I've had both and the 8 is my most used scope, mostly because of the above
the 8SE has almost 2x the light grasp of the 6SE because of the larger mirror and will therefore show you more detail (conditions permitting) on practically anything you point it at. The down side to the 8 is that the 8" tube is getting a little bulky for the single arm mount and if you touch the scope it can wobble a bit...this can mostly be avoided by setting up on softer ground (concrete or wooden decking is not good) and by taking care when grabbing the focuser. Also, if the difference between the day time and night time temperatures is substantial, you may not get optimal views at higher magnifications because the optical tube is captive and can experience internal turbulence! You can assist cooling with a "cat cooler", or decide this isn't suitable for you. In Sydney, the temperature difference doesn't seem to cause me significant problems (and I upgraded my tube to one with vents)
Visually, you'll see more with the bigger scopes as Allan mentioned, although personally I feel that 8" is the sweet spot between seeing good detail and portability. There's always bigger scopes, but they're never as portable and the flex tube Dobs in bigger sizes are still big and heavy. That's not to say they're not worth it for the views...the middle ground might be a 10" goto Dob, gives your the benefit of tracking and goto without losing too much mirror size...but I'd recommend you see one first as they're still not small or light, but it depends on what is most important to you.
Photography is a complicated subject... the Neximage camera is only suitable for capturing footage of solar system objects, not for the long exposure times needed to capture deep sky objects effectively. For that you'd need a DSLR camera or an astronomical CCD, together with an equatorial mount. If you want to get into deep sky photography, I'd suggest a short focal length refractor to start with, but there are many expert imagers here on IIS with quite varied equipment that can advice you better on that subject. The 6SE or 8SE are quite capable when it comes to planetary photography because of their relatively long native focal lengths.
If you aren't familiar with equatorial mounts, either go see one somewhere before you buy...there is a bit of a learning curve to get started (especially without a pole star!), but like anything becomes easier with practice. An EQ6 is a heavy beast - I use one with my larger scope - but seems to be the standard response for entry-level deep sky photography.
Regarding filters...Moon filters seem to be a personal choice thing. When you're looking at the Moon, it's bright but your eye will adapt. For nebulae, I'd recommend getting started with a UHC type filter rather than an OIII (which you can add later)...but if you observe somewhere dark you might be surprised how much can be seen without these...the Orion, Tarantula and Eta Carina nebulae are all incredible to look at without, you just need a dark enough sky
