Hi All - Firstly, thanks for the informed replies!
I think the key bit of understanding I was missing was that - "most flash-capable incident meters can automatically detect and measure a flash”. This is great and means I can trip the flash manually whilst metering (although I’d probably need a friend to help trigger the flash as I would need to be metering near the subject.
BillC - I also really appreciate your comments. I like the idea of holding a note of common flash/appeture/shutter settings for different conditions. Hopefully I can build this over time with some trial and error.
I was actually thinking about metering everything with my 5D MKII so I don’t waste film, then transferring the settings over to the Mamiya - will this be a reliable thing to do?
I also get what you’re saying about some situations not really being right to meter, but most of the people I’ll be shooting will have 'signed up’ to take some photos with me, so Im happy to take some time before to meter properly.
Finally, I know the Sekonic L-308S does look to be the best mid-level meter, but I’ve spent so much on Photography gear this month, I’m really hoping I can get something a little cheaper - any suggestions would be amazing.
Thanks all - great group!