Why get a bigger van?

I have a SWB Transit (low roof) and I'm wondering whether it's worth getting something bigger. I'm familiar with the obvious pros and cons (costs more to run, but you can take on more work and charge more etc) but it seems a case of six of one, half a dozen of the other. I get 40+mpg out of the Transit, and it's handy in car parks.

Do you actually make that much more profit with a bigger van? (If so, it's presumably sensible to buy the biggest van you can possibly afford.)

I'd be interested to hear from anyone who's upgraded in the past, and can say 1) why they upgraded when they did, and 2) whether there was a big improvement in earnings.

our euro 5 125ps tranny lwb m/r which is only an inch or so lower than a h/r (inside) is doing 37mpg

That's slightly better than I thought.

How often do you kick yourself that you can't do a job offered because your van is too small? some people have loads of big van work some don't, personally I rarely get asked for anything bigger than a small/motorcycle, and of coarse if your doing pallet type work your are at the mercy of the muppet on the forklift to unload you, if your behind a 38 tonner then prepare to wait!

the newer berlingos etc carry almost as much weight as the older swb but do more to the gallon,

depends on the work you are doing,

There aren't that many jobs I have to turn away at the moment, but I could put in offers for more loads on mtvan and CX...