Citizen, thanks for helping me out.
I decided on getting the tamron 17-50 instead of the 17-55 and have since bought a flash. In the future, I plan to purchase the 70-200 F4L and maybe the sigma 50 1.4.
I had a chance to try out the 200AW in person, and it's a bit too large for my liking. The reason I was looking at the 100 AW, or the Slingshot type bag in the first place, is because I'm planning to drive to photo destinations on my sport bike (spring is here! )
and need a bag that's small, but versatile enough to carry the equipment I currently have, but the two lenses I hope to buy in the future.
Here's my proposed layout.
My flash would be inside the top compartment in it's own soft case,
The 70-200 would be at the top laying horizontally, where your lens hood is sitting,
My 40D with the 17-50 would sit where your setup is,
and the sigma would be where your extra lens is (at the bottom right hand side)
I've seen shots of the 100AW with the 70-200 and a 40D with lens attached. It looks a bit cramped, but still works. My only problem is that the sigma 50mm is a beast of a prime and I'm not sure if that would fit.
If worst came to worst, I could put that on the top comparment and bring the flash down, but I'm afraid that it might fall out somehow.
Am I being irrational, trying to stick with the 100 AW, than go with the 200?
Right now, I just don't have enough equipment to fill a 200 and if the 100 could fit my ideal setup, I'd prefer a more compact bag.
Thanks in advance for your help!