My two pence:
As a gate agent working for AA (for the record I'm BA Bronze) I think that this is a great benefit to OW Rubies. I can confirm , at least on AA flights departing Houston, that Rubies are not a considerable amount of passengers. The most is by far Sapphires. On average I would say that there are no more than 8 Rubies on a full flight to Dallas (serviced with an MD80) on a Thursday (busiest day for business passengers).

This will be a welcomed benefit to BA Bronzes. When Rubies fly BA, the only benefit they actually have is seat selection 7 days in advance and CW checkin. That's it. The addition of this perk will be a step in the right direction.

For comparison sake, AA Golds (equivalent to BA Bronze) passengers get 2 free bags, F class checkin at out stations and J class checkin where available, Priority Security, Priority Boarding and they are able to select any seat (including Main Cabin Extra Seats until the end of the year) from the time of booking. That truly makes BA Bronze status look worthless. When knowledgable BA Bronze passengers fly with us, they are pleasantly surprised that they get all of these benefits. The only things BA bronze don't get when flying AA is the ability to get a complimentary upgrade. This change will give a very slight benefit to Rubies when flying BA, however it is nowhere near the amount of perks a Ruby would get when flying AA. ( to those of you complaining over Bronze benefits, please brace yourself if you ever fly AA). I'm sure an AA Gold would be surprised at the expressed lack of benefits while flying BA.

The BA boarding process needs to be changed. Ours works wonderfully- Domestic (euro)
1. F class, then (after they gather up in the queue) AA Executive Platinums and Emeralds
2. Platinums and Sapphires
3. Golds and Rubies
4. Priority AAcess (some pax get this benefit with their ticket purchased eg. Y class tickets)
5. Group 1 ( a paid benefit or passengers seated in Bulkheads or passengers with an AA CC)
6. Group 2
7. Group 3
8. All Aboard

For 3 class flights (LH)
1. F class
2. Executive Platinums and Emeralds
3. J class
4. Platinums and Sapphires
5. Golds and Rubies
6. Priority AAcess
7. Group 1
8. Group 2
9. Group 3
10. All Aboard

This may seem a lot but actually takes very minimal effort from us agents to carry out. It lets status passengers actually get on the plane first if they so desire as well. It also keeps the priority queue open to allow for leisure boarding for premium passengers. A practically free method that BA could introduce. BA look to AA to learn how to carry out this process.