Tried this out today in one of those 'Memory Stick PRO Duo Dual slot adapters', basically you use two microSD cards in one and then use it for your PSP, or camera, or whatever.  Worked great, two 32 GB cards were just a little cheaper than one of these and I wanted my nephew to upgrade to 128 GB if he wanted.  The adapter didn't say it would work with XC and we were worried that the PSP would have a problem with it but it all worked out great.  He is upgrading to 64 GB from 2 GB, it was a little overwhelming.  He has lots more space now and might get another one of these cards to put in the same adapter.  I'll update this if anything goes wrong.