I've had to go through the pain of trying to shift marks from one format to another,or even from an earlier plotter to a later one of the same make ,quite a few times over the years.Or got caught in a complete dead end like the Sitex I bought less than a decade ago.

The old bloke up the road came to see me the other day, asking if I had a spare GPS aerial, as the external on his 90's Lowrance X-15 had died. Couldn't help him as I had passed all mine on to good homes over the years. He was becoming resigned to getting a new unit, wanted to know if his marks would move over. I said I thought Lowrance had stuck with one format, wasn't sure,so he gave me his memory card. Had a tiny Data.USR file, , on an SD (MMC) card, apparently last updated 1/1/2000.  I went into the menu, found file transfer,did it to a new file name,still showing last updated 1/1/2000. then it dawned on me that the card was probably so old that it was suffering from the Y2K affliction! Transferred them to a micro SD. Anyway, I backed up my Elite-7, stuck his card in, downloaded, and there were his marks, over the top of mine. I mean, really over the top of some of mine, because I gave them to him when I was crayfishing! I was a bit surprised that there were no "version" issues, and that it didn't wipe my(backed-up) marks when it loaded, but there you go.

Stick with Lowrance and your marks are future-proofed.