In IRROPS there is a lot more ability to have beneficial changes
. You don't just have to accept whatever you are given if there is a cancellation. If the day before the chosen flight is better for you then ask for it!
For example, I recently booked some AS award flights using QF points. A few weeks later I found that there was a schedule change and my 2 hr connection became 8 hours. I rang QF and they said "no availability shown in the system for a better connection - but I'll message AS and see if they can open up seats that you want". A day later I rang back to QF and the preferred seats had indeed been approved. This wouldn't have happened without the direct phone operator's actions.
That only works easily when the miles are redeemed on the same scheme as the change
Wirh BA miles, BA will inly make the change where there is award availability - QF may or may not agree to make changes from customer
If there is award availability, then its easy of course