Slingshot 100 OR 200 (AW)

Definitely the 200 if you are planning on getting two other lenses beside your current kit lens and a 580ex... especially since it's a $20 difference.

Go with the 200.
I have it and wouldn't want anything smaller. I also keep a Canon shoulder bag for overflow and items that aren't everyday. The 200 is not ungainly in size. In fact, for a back pack it is modest. You can always put less in than it will hold. What do you do if you buy one too small?

I have the 100, and while I love the small size, I sometimes wish for the 200.
The 70-300 IS barely fits in the bag at all. Mounted, it can fit, but it is a stretch on the zipper, and frankly I would not want to keep it this way. The 70-200 will definately not fit whatsoever, unless there is no body in the bag.

There's also the new 300 to consider. For me, I went with the 200 and I'm happy. I looked at the 100 but it was just too small for my liking. I tend to pack mine with as much gear as I can which explains why I wouldn't buy the 300 - far too much weight to lug around on one shoulder which defeats the purpose of the Slingshot series. My 200 holds my 20D with grip and 24-105 attached, a 580EX, Tokina 12-24, Canon 50 1.4, mini tripod, Lightsphere PJ with top, two battery chargers (for AAs and BP511), WhiBal, filters, CF cards, Lenspen etc. That's a lot of weight, although, I did carry it around all day in Hawaii last summer it wasn't a painless experience.

Thanks guys! I did end up getting the 200 a long while ago.. though the 300 seems pretty cool.

Here's a quick review for anyone else who is trying to decide: the 200 is good. though the sling action can sometimes wrinkle up your clothes, not too big of an issue. the bag is nice and roomy, and can be customized with the velcro padding things very easily.

my biggest issue is that it cant fit the 70-200 IS mounted. of course, to do so it'd have to be like HUGE (just simple geometry because the 70-200 is so long). being able to have it on my back and then pull it out without taking off is great though - its a lot more convenient to wlk around with than my toploader 75.