No reason. My bike also had a built date of June 2025. So as long as EU and OZ market builds are the same spec. There should be no issues.
When I bought the bike the dealer told me it wasnt straightforward. But maybe they mean its not as simple as pre installed bikes. I believe the extra hassle was changing coding to allow the central locking to work. As essentially they have to change the build spec of the chassis. Then have factory servers confirm and accept. Then the send the coding to the bike. Its not like the old days where they csn manually just change a measure block . The actual data card of the bike needs to change. I think this is what creates the issues.
For parts I believe it is a partial loom, plus the side connection points etc.
One thing yo add also. With the Performance model suspension there are no issues either. It has range to adapt and even with panniers loaded the bike compensates and in Dynamic with load it actually feels better sometimes. Maybe because the load forces it to really jack itself up and add alot more support.
I know for sure there was a dealer in UK who has a demo with panniers installed also. So for sure it is possible.
Itd mainly BMW red tape. Ad the V max etc and rated subframe loads need to change with panniers etc. You know how the world is. Someone somewhere will fully load the bike with a 18 stone passenger plus full panniers and do a V max run . The bike will have a speed wobble or crack a subframe or something and they will claim BMW.