A CF card is a CF card is a CF card; if they conform to the spec, they'll work. Here's my story:
I had a card from my Canon camera, I cleared off all the pictures, I read the instructions, I put the two files in the root directory, and...
It didn't work. The C-80 just ignored the new card.
I surmised that there might be some residual camera-related data on this several-year-old card that was preventing the Raymarine unit from reading it properly. I decided to format the card, erasing everything on it and starting from scratch.
Once I started down this road, I had a choice about which file system to use: FAT or NTFS. Ah-ha! The problem MIGHT be that the card is formatted with the wrong file system. I went to the Raymarine site to learn what file system they require; it's FAT.
So I reformatted the card using the FAT file system option. Re-loaded the two files, and took the card back to the boat. It upgraded just fine.
So if you've got an otherwise good CF card and you can't get it to work in your Raymarine multi-function display, try reformatting it before you go out to buy a new one.