Hello Mirek --

After reading about your concerns and concerns expressed by other folks, I wrote and posted a quick analysis about NAND flash memory retention: http://sandsoftwaresound.net/nand-flash-data-retention/

The bottom line: NAND flash write and erasure is relatively infrequent when using a musical instrument. We don't overwrite/change waveform memory very often and we don't frequently write new performances/patches to user memory. We should get at least ten years retention and probably much more. NAND flash is used throughout industry with success and there are software techniques which improve or assure data lifetime.

I worry more about hitting the wrong button at the wrong time -- accidentally overwriting my own work through carelessness! Thus, I always keep my work backed up and safely out of harms way just in case. You are backed up, right? 🙂

All the best -- pj