I've just ordered a Carradice Nelson LF seat bag. Any feedback from those who own one now or in the past?

I use the slightly larger Camper LF. It is my absolute favorite bike-related purchase. I use it with the Carradice Bagman QR adapter and support. I change/shower at work, so I put clothes in the main compartment, toiletries in one side pocket, and bike tools/tube in the other side compartment. I've had mine for 2+ years and it has held up perfectly--no tears or anything. Just getting better with age.

I've had a low-saddle longflap on my commuter for the last 25 years.
Indispensable.

Looks pretty ratty but it still works fine.

23L Carradice Super-C. Love it, especially with the QR. Will be putting one on a new bike I'm building at the moment as well.

The guy that inspired me to think"hey, I should be doing that" had a Caradice bag hanging from a Brooks saddle. I've had the B17 for years, but have liked my Nashbar rack trunk so much I've never had the urge to get the Caradice bag to go with it.