I have a Slingshot 200 here and I fucking hate it. My old man gave it me when he sold up but it goes on the wrong shoulder for me. I would try one in a shop before you buy. Crumplers are good, plenty of range. I have a few of them now and wouldn't buy anything else TBH.
As far as filters go many don't and many do. I do with most of mine but wouldn't put cheap filters on a lens I paid hundreds for so I tend to use B+W MRC UV or the Hoya Pro series ones. Have a look [Only registered and activated users can see links. ] for them as they are pretty cheap on there.
I have a SS200 and I like it, its plenty big enough for my A700 (med sized body), my 82mm sigma 24-70 and a large 70-300mm and room for another couple of average sized lenses, or a lens and a flash. It can be a little snug but its rare i take everything at one time and I think this sort of bag isn't really suited to the weight of that amount of kit if you are going to have it on your back for extended periods.
Same with 'root on the filters, i have a sigma branded one on my 24-70 but a cheap jessops one on my 70-300 and i often get ghosting when shooting gigs with bright spotlights etc, I really need to replace it.
[Only registered and activated users can see links. ]
Just the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown.