Thanks for all suggestions.
After a sunday afternoon of tests i want to share my results with you ROM READING:
It simply WORKS ! in Windows and OSX, with all emulators (kega fusion, gens, snes9x, zsnes)JOYPAD COMPATIBILITY
This worked out of the box too except for the Kega Fusion emulator under OSX (it's a know problem already discussed in this thread http://forum.retrode.org/index.php/topic,11.0.html
This took most of my time.SNES
On OSX i wasn't able to get it to work.
ZSNES doesn't let me input the correct path of the Retrode unit (/Volumes/RETRODE) cause it doesn't recognize character like / and other.
SNES9x let me set the correct path but it creates a rom_name.srm.ooops
when i save.
I think it's for this problem http://www.retrode.org/documentation/troubleshooting/troubleshooting-saving-files-to-the-retrode-does-not-work/
I didn't try the cat thing but it probably works.
On Windows SNES9x saves worked out of the box (Donkey Kong Country and Super Mario All Stars) configuring the correct retrode path.
I saved and started the game on a real SNES ... it worked.Mega Drive
On OSX i didn't test anything.
On Windows i wasn't able to get it to work with both Kega Fusion and Gens.
I try to save the game directly to the cart but saves weren't recognized when i plugged it on a real Mega Drive.
Same result when i saved to the disk and then manually copied the file on the retrode unit.
Games tested were: Wonderboy 5 in Monster World, Shining in the darkness, Shining Force I.
Carts are not broken cause when i play and save them using a real Mega Drive they work fine.
If someone has suggestions for the Mega Drive saves it will be really appreciated !