I had a old firmware on my GPSMAP 525s, but I tried to get unlock a map with a 8 GB SD Card... But now I got the map working (using 2 GB SD Card). I made this post to warn other people about the problem, since I used many hours to actually find this out.

Here is a breakdown of what sized SD card can be used with the devices and their software versions:
GPSMAP 420, 430, 440 series v3.10 and below - 2GB SD card
GPSMAP 420, 430, 440 series v3.20 and above - 8GB SD card
GPSMAP 421, 431, 441 series with any software version - 8GB SD card
GPSMAP 520, 530, 540 series v3.10 and below - 2GB SD card
GPSMAP 520, 530, 540 series v3.20 and above - 8GB SD card
GPSMAP 521, 531, 541 series with any software version - 8GB SD card
GPSMAP 525, 535, 545 series v3.10 and below - 2GB SD card
GPSMAP 525, 535, 545 series v3.20 and above - 8GB SD card
GPSMAP 526, 536, 546 series with any software version - 8GB SD card
GPSMAP 600 series - 8GB SD card
GPSMAP 700 series - 8GB SD card
GPSMAP 4000 and 5000 series v4.00 and below - 2GB SD card
GPSMAP 4000 and 5000 series v4.10 and above - 8GB SD card
GPSMAP 6000 and 7000 series with any software version - 8GB SD card

Question:
Will the unlocked map still work if I update to the newest firmware version?