One thing that has not been mentioned with regard to BRMs is that they are listed in ACP's international calendar, which would be an advantage for an organiser who wants to attract riders from abroad. Not that a bog-standard 200 is likely to be a major draw outside the immediate area, but you never know!
Anyway, to go back to the original question, what are the pros and cons for an organiser of listing an event as a BRM? As far as I can see, they are
Pro
- Allows riders to use them as qualifiers for international events (not only PBP).
- Count towards ACP SR and other awards.
- Sense of being part of the wider randonneuring community (the ACP stamp in the brevet, listing in the ACP calendar).
Con
- No instant validation option.
- Over-distance restriction.
Two of the Pro reasons are practical, one is purely subjective and has no practical benefit. I don't think anyone believes a BRM is in any meaningful sense better than a BR, but all are valid reasons for some riders to prefer BRM events.
As we've ascertained, the set time limit for BRMs is neither a pro nor a con, since in many cases it allows the rider more time to complete the distance than a BR.
The reason for the question in the first place was because I'd read something about the pros and cons of BR vs BRM, which mentioned that some riders 'seek out' BRMs. I can't for the life of me remember where I read this, though - I thought it was in the organisers handbook, along with the bit about the increased validation fees, but I can no longer find the relevant passage. Maybe it was an out-of-date version of the handbook I was looking at. Obviously the bit about increased validation fees is no longer true anyway.