Thanks Antoine.
I've already had information back from SAP support stating they have reproduced the issue and reported it as of PA2.5 for XI 3.1 SP6 or above (as that's what's officially supported). We're in the process of moving to 4.1 or possibly 4.2, hopefully in the next couple of months, so won't be an issue for us for much longer (fingers crossed).
Kind regards
/Magnus