[Hr2]

Well, it's actually not so much the timing issue. SM contains a quantize option, which means that you can make all the 64th and 48th notes turn into the closest 16th note. However, unless you have the entire song memorized, or that it's extremely simple and repetitive, then you're probably going to miss some little sounds. The little sounds are what makes a song unique, along with coherent and consistent patterns. It can take half an hour or sometimes more to perfect a pattern, and record mode affords much much less than that :P

It's just not a good idea, but some people use it for specific parts. For example if someone is speaking and they want to sync to the voice, they will put it in record mode for a few seconds to sync to the syllables.