I’ve got a Lowe Pro Slingshot which is pretty good. It’s the 200AW, which is the second biggest in the range. I can only just get a D80 with 18-135 on it, plus a 70-300mm VR lens into the main compartment.
If it wasn’t for the bulk of the 70-300, then I could probably get two lens’ in with the body & 18-135 but it’s worth trying your kit out in one before you decide on a size – I didn’t and wish I’d gone for the size up.
There will be no way of wedging a flashgun into the bag when i finally get round to buying one.
Apart from that it’s a good bag. Only other gripe (apart from size) is that it can be awkward to change lens’ over. Not sure if that just relates to this bag though or bags in general – I imagine one of the large, square bags that has a shoulder strap and sits on your hip would make it easier to swap lens’.
Also as already said, I can’t imagine this bag being any good for cycling with unless gentle cruising along.