What exactly is lost by flashing the FS?

[zacher]

AFAIK there is no quick way to save the configuration (be sure to back up the files like ring tones and themes). Some of it can be set in the custpack but it may take longer than just doing it by hand. I recommend modifying whatever custpack you use for whatever easy changes you like as you will probably use it again. I set the default ring volume higher and things like that that are easy changes.