gewecke, I have a PSR800 and I love it. As for it being picky about the MicroSD card brand, I haven't found that to be the case. I have an 8 gig, no-name card I bought from e-Bay that didn't work at first. I used a program called SD Card Formatter to change the format from NTFS to FAT32, 32 kB sectors and it worked fine. The scanner will NOT work using cards formatted as NTFS but it does work with either FAT or FAT32. I even tried a 32 gig card and that worked. The manual says to use the EZScan program to format the card but EZScan won't format a card it doesn't recognize.
One thing to note, the larger the card, the longer it takes the scanner to boot.