I have a Hadley Pro - I'd say you might struggle to get a Macbook and camera kit comfortably in it to be honest (especially the 5D+50mm). The Macbook and GF1 would probably be ok, but the bag is actually quite small despite appearances. I use mine for GF1, 20mm, 45mm, LVF + bits and bobs and it's a good fit for that, with some space to spare. There are a couple of front pockets, so I guess you might be able to get a body in one of those to leave room for the Macbook in the main compartment.
I can try some permutations later tonight actually, as my wife still has her 13" Macbook knocking around while we try to sell it, so I'll see how well it fits in and how much other stuff you could reasonably get in if you like, as I might be wrong about what you could get in.
The bag isn't designed to carry a load of stuff however, so weight and therefore back/neck etc pain should never be an issue. I actually find the Billingham's very comfy (more so than backpacks I've had - although the Kata R-103 was pretty darned good), especially if you augment them with one of the larger shoulder pads SP40/50 for example.
For just the GF1 and a couple of lenses, bits etc I use the Hadley Digital, which is actually larger than you might think. I also have a Billingham 335, which will fit lots of camera stuff, plus laptop (only just mind you) and plenty of other effects in - used as hand luggage on numerous occasions.
It's a very painful realisation that there appears (for me at least) to never be one bag which will be everything you want it to be - it'll either be too big for times when you want to carry less, or too small when you want to carry more etc etc. I've been through lots of bags - Lowepro, Kata and so on. I like the Billinghams best, but then they appeal to my old fashioned sense of quality and aesthetics.