You do realise that SDXC isn't really a hardware bump, don't you? It's just Microsoft pushing another crappy FAT derivative...
The 104MB/s provided by SDXC might be a hardware issue though, as SDHC only supports 25MB/s.
If they are just going to bump up the speed from 50Mhz to 200Mhz, people will have to be a lot more careful with there traces.
ExFAT doesn't mean anything - its just the preferred file system. You can reformat and put ext3 on there if you want. (It had to be changed due to FAT32s limitations)