Fear of 'losing data' during repeated over-writes

Like Eternal Sunshine of the Spotless Mind, I fear that if I 'lose' some of my 'programming', I'll lose some of ME in the process. I don't actually want to lose my MEMORIES, just the pain, and the painful habits, associated with those memories.

But in Spotless, the original versions of the main characters leaked through the 'de-programming', and they eventually reverted to their old selves. The 'wiped slate' was not thorough enough - perhaps *too* clean a wipe would remove essential functions, and not just 'surface' personality traits.

Query: *Are* such 'charactistics' only on the surface? or are they deeply integrated throughout the person's being? never thought about it before, but maybe that's the whole point/central question of the movie. If we erase our memories, do *we* disappear, as well?