Writeback is as handled as simply as just copying back the entire $9D95 area to the program's space, so I guess the same goes for SMC. DCS does it more "intelligently". (that means: check if anything has changed, for "garbage collection" purposes)
EDIT: @Seren: MOS programs are STILL copied from archive to the 9D95 area, they don't run from archive, so there's no problem in using SMC/writeback.