I have not ..
The Brooks Pro I got 30 years ago, never had any loops at all , I added bolt to the rails bag loops , steel .
Yours would have survived if just a wee tool bag was fitted at most, ..
but, D'oh ! .. tore out when you packed up a Carradice Camper Nelson long flap , spring action and
lock and chain probably did it, shifting around and all . was the bag strapped to the seat post too,?
Overloaded sheared off, as its just a grommet in leather , adding just a bit of stability, at most .
and another way to support the load rather than a grommet in a piece of leather would be better..
http://www.sjscycles.co.uk/thorn-acc...22924/?geoc=us
there are Brooks saddle frames that have the bag loop on the rear steel part instead, I think .. that would be a better option
something else in the Brooks catalog . B67? Wire loops not looking real sturdy though..
http://www.brooksengland.com/catalog...eavy+duty/B67/
I have a Carradice (superC) on a separate sub frame and a rear rack . (I was also adapting non leather saddle)
Decades of use .. Pro was bought in the mid 70's..
It's been used on a few long bike tours , but then the load was primarily in panniers ..