From MANUAL
New Style can be transferred to the Flash ROM memories(1-8), ...
You can load one Music Style to the EM-50LDisk User memory and use it as if were a 73rd Music Style.
The Style data in this momory are only available until you switch off your EM-50 or load another Style.
My comment:
*Disk user memoy loading time is very fast.
*You can use all Roland Style .(MSD, MSE, MSA).
*8 Styles in Flash is grouped, load & save as on file, but you can create new group file with 8 individual Style file.