the files needed are only those you have used. If you have used no user pads, user effects, sound edits, panel banks 1 - 10 etc in your easy record there is no point saving them since they contain useless information. If you use a preset style you don't 'need' to save the composer.
The difference in loading time is very noticeable on floppy disk, particularly with pre nx models, but the speed of SD masks the speed difference. However you will noticeably fit more files on SD with selective saving, particularly with the required formatting.
It's all described in the book