I haven't got a Lowepro slingshot, but I looked at them. Someone here (may have been nick) pointed out that they can get rather heavy over one shoulder. I'm still considering the Slingshot 100 for times when I'm only taking one lens and a few bits and bobs, but that assumes that I know exactly what I'm doing.
I have a Lowepro Fastpack 200 and it isn't half bad, but there is one thing I would note- if I got the same type of bag again, and not another make or model, I would get the Fastpack 250, which has a laptop compartment as well. I wouldn't use it for a laptop, but it would be great for larger items such as reflectors or an A4 notepad as I find that the 200 is very restrictive in that respect.
One more thing- SHOP AROUND. I eventually got the Fastpack 200 for less than £40 delivered and it won't take long to find out how much some sites are selling it for. One was in the region of £90.
